Chapter 1. Present State of Approaches for Ensuring Safety against Tsunami
This chapter consolidates the history of tsunami assessments and approaches employed to ensure
the safety of nuclear power plants against tsunami.
1.1. History of tsunami assessments and approach to ensuring safety against tsunami since 2011
Tohoku earthquake
1.1.1. Research on tsunami by the Japan Society of Civil Engineers
The Japan Society of Civil Engineers is a key presence promoting the public interest by
ascertaining long-term social infrastructure and system needs as well as engaging in exchange andevaluation of research, scholarly study and technology on how social infrastructure and systems,
capable of flexibly addressing such needs, should be structured and provided. Also, the Japan Societyof Civil Engineers is an academic society that undertakes research on tsunami and the development oftechnology for Japan with its tsunami-prone regions, such as the Pacific coast and the coastline along
the eastern margin of the Japan Sea.
Coastal engineering is a type of civil engineering that studies, among other things, natural
phenomena, structures, plans for preserving and developing coastlines and the accompanying water
areas. The Japan Society of Civil Engineers’ Coastal Engineering Committee publishes annual
collections of papers on coastal engineering and holds lectures and other talks in connection with these.
The first such session was held in 1954. By 2015, the total number of such sessions has reached 62.
At the sixth lecture (1959), a paper entitled “Tsunami Countermeasures for the Sanriku Coast” (Sasaki,1959) was one of the first publications released during the initial period of the society’s tsunami
research. In this paper, an author affiliated with the Iwate Prefecture Civil Engineering Department
discussed methods for designing coastline structures based on historical tsunami and other events thathave occurred along the Sanriku coast. The conclusion alluded to the uncertainty of tsunami
phenomena, and stated that open spaces should be left behind coastal dykes as well as mentioning thenecessity for a process to evacuate people in cases where structures are unable to hold back a tsunami,
which we now understand as similar to the current approach adopted in tsunami countermeasures.
Subsequently as well, papers on tsunami have continued to be published, increasing to the 1,000
compilations that have currently been released. This number has increased since the 1990s, andresearch has been particularly enthusiastic since 2000. This pace was significantly influenced by theincrease in tsunami research due to the disasters associated with the 2004 Sumatra earthquake tsunami
and the 2011 off the Pacific coast of the Tohoku earthquake tsunami as well as the increase in tsunami
research on account of the Japanese government’s promotion of measures to counter tsunami occurring

Appendix 1 - 1

along the Nankai Trough since 2003 (Central Disaster Management Council, 2003) (Fig. 1.1.1-1). In
addition, tsunami research results have frequently been presented at Earthquake Engineering
Symposium, which have been hosted by the Japan Society of Civil Engineers Earthquake Engineering
Committee.

Figure 1.1.1-1 Example of tsunami source region of Nankai Trough by Central Disaster Management
Council (2003)
1.1.2. The Nuclear Civil Engineering Committee and the Tsunami Evaluation Subcommittee(1) Prior to the 2011 Tohoku earthquake
The Nuclear Civil Engineering Committee was established for the purposes of conducting
research on issues related to civil engineering technology pertaining to the use of nuclear powerand contributing to the promotion of scholarship and technology. The Tsunami Evaluation
Subcommittee was launched in 1999 to conduct research on tsunami.
Two turning points led to this development. One was the compilation by the seven relevant
government ministries and agencies of a guide on tsunami countermeasures (National Land
Agency et al., 1998) to be used for disaster administration, an endeavor that was prompted by the
1993 Hokkaido Nansei-oki earthquake and tsunami. The guide indicated the need to take into
consideration not only the largest historical tsunami, but also the largest supposed earthquake
tsunami. The second point was that standardized methods had not yet been compiled for assessing
tsunami with respect to nuclear power plants. After approximately two years of deliberations, theresults of technological progress and knowledge developed about tsunami sources and numericalcalculations were compiled, thereby consolidating methods for configuring design tsunami for
nuclear power facilities. These results were released in a publication entitled “Tsunami
Assessment Method for Nuclear Power Plants in Japan” (Japan Society of Civil Engineers, 2002).
These results served as the foundation for “Chapter 4. Tsunami Height Assessment”, which
was published in the Japan Electric Association’s Nuclear Power Plant Aseismic Design

Appendix 1 - 2

Guidelines (Japan Electric Association, 2008). An English version was also prepared and released(JSCE, 2006). These guidelines were also referenced and quoted in reports released by theInternational Atomic Energy Agency (IAEA) and the Nuclear Regulatory Commission in the
United States (IAEA, 2011; NRC, 2009), and have been recognized to a certain extent
internationally as well (Fig. 1.1.2-1).
Since then, reviews have also been advanced on probabilistic assessments of tsunami height(Japan Society of Civil Engineers, 2011a) and changes in submarine topography due to tsunami(Fujii et al., 2009; Ikeno et al, 2009; Fujita et al., 2010) along with other issues.
(2) After the 2011 Tohoku earthquake
After the 2011 Tohoku earthquake, the Japan Society of Civil Engineers set up 10
committees established to conduct their work for a fixed period of time, among these werecommittees that would address particular topics, in addition to the society’s permanentcommittees. Expert knowledge was accumulated, compiled into many proposals and published.
For example, a committee studying tsunami estimation and disaster reduction took into accountthe lessons learned from the damage wrought by the massive tsunami triggered by the 2011
Tohoku earthquake and proposed methods of incorporating these lessons over the short and longterm to counter disaster from massive tsunami (Japan Society of Civil Engineers, 2012).
After the tsunami damage to nuclear power plants from the 2011 Tohoku earthquake, theNuclear Civil Engineering Committee held a session to report the results of tsunami research on
November 2, 2011, at which a report was presented on the direction for tsunami configurationthat takes into account the Great East Japan Earthquake as well as methods for configuring
tsunami height (Japan Society of Civil Engineers, 2011b).
A committee was established to research the special topic of nuclear safety technology,
which the Nuclear Civil Engineering Committee was central to such deliberations, and proposeda new framework for earthquake and tsunami resistant design as well as a risk management
system (Japan Society of Civil Engineers, 2013). Specifically, the proposal stated: “A newconcept of ‘anti-catastrophe’ is proposed in addition to the conventional concept of ‘safety’ forperformance vis-à-vis an earthquake or tsunami. The assurance of ‘anti-catastrophe’ is importantfor handling events or other situations that exceed the standard ground motion or standard
tsunami”. This approach is in accordance with the concept of defense in depth, which is the basis
for ensuring nuclear safety, and, furthermore, the proposal broadly took into consideration ageneral ease of understanding such information. This publication is a compilation of relevant
tsunami assessment technology with a view towards contributing towards this framework as well.
Following the 2011 Tohoku earthquake, the Tsunami Evaluation Subcommittee collected
and analyzed information about this tsunami disaster. For example, the height of traces of tsunami

Appendix 1 - 3

obtained from surveys and the results of calculations of tsunami based on many proposed tsunami
source models were compared for this tsunami (Kurita et al., 2013). Useful results were obtained
for methods for configuring uncertainty in probabilistic tsunami hazard analysis, such as thevariance of calculation results for the run-up height records of historical tsunami increases
according to the distance of such traces from the coastline. After taking into account the results
obtained from these reviews of the 2011 Tohoku earthquake, research results, which had been
compiled since 2002, were added to put together this publication.

Figure 1.1.2-1 Report of tsunami hazard assessment by U.S.NRC and page quoted from tsunami
evaluation assessment by JSCE in it.
1.1.3. Atomic Energy Society of Japan
Since the accident at the Fukushima Daiichi Nuclear Power Station, the Atomic Energy Societyof Japan (“AESJ”), a group of experts specializing in the nuclear field, has progressively contributed
to resolution of the accident and other aspects, and continued to fulfill its responsibility. Within that
context, the AESJ launched an accident investigation committee, which published the results of its
efforts in a final report (AESJ, 2014; hereinafter “AESJ Report”). The AESJ Report consolidates
analyses of the Fukushima Daiichi accident as well as the conditions of other stricken nuclear power
plants. Moreover, deliberations were conducted both inside and outside the AESJ to put together thefundamental causes of the accident as well as proposals.
This report classifies the fundamental causes into direct factors and contextual factors. It further
breaks down the direct factors into measures to counter the direct impact of a tsunami in cases where
the design basis is exceeded, measures to counter a severe accident arising as a result of suchexceedance, and measures for accident mitigation and avoidance during an emergency, and the report

Appendix 1 - 4

points out that these three measures have not been sufficient. In addition, as to the contextual factors,
the report notes problems concerning the awareness and stance taken by stakeholders in relation to theassurance of nuclear safety.
The recommendations, which were developed through an examination of these fundamental
causes, are comprised into 50 items classified into five categories (Fig. 1.1.3-1). The focus here is on
the content related to tsunami countermeasures in recommendations I and II, and summaries are given.
Recommendation I “Basic Items of Nuclear Safety” touches upon first clarifying the goals of
nuclear safety and the necessity for systematizing such goals, and states that the way to realize suchgoals requires achieving a greater understanding of defense in depth, which has been previously
recommended, and enhancing its application.

Figure 1.1.3-1 Recommendations of the AESJ Investigation Committee (AESJ, 2014)
Recommendation II “Items related to Direct Causes” (Fig. 1.1.3-2) discusses the necessity of allencompassing assessments of many external events, including earthquakes, in terms of “1.
Strengthening measures against external events”. More specifically, the recommendation calls for firstunderstanding the vulnerabilities of a nuclear power plant and specifying the responses by conducting
a comprehensive assessment of anticipated external events, including not only earthquakes andtsunamis, but also fires and other such events, and for addressing the vulnerabilities where an extensive
loss of safety function may simultaneously occur in response to an external event resulting in a criticalsituation (cliff-edge measures). Under “4. Enhancement of the nuclear safety assessment technology”,
the report discusses how the utilization of probabilistic risk assessment technology should beincorporated, which is able to consider a variety of uncertainties in order to increase the quality ofpredictions, and the utilization of numerical calculation techniques, which employ the latest computer
performance for analysis of natural phenomena and other events.

Appendix 1 - 5

Figure 1.1.3-2 Composition of Recommendation II of the AESJ Investigation Committee (AESJ,
2014)
1.1.4. JSME Japan Society of Mechanical Engineers
The Japan Society of Mechanical Engineers (JSME) launched two task forces immediately after
the 2011 Tohoku earthquake, conducted investigations of the damage from the perspective of
mechanical engineering, and compiled the results. Furthermore, the JSME put together proposals fromits broad perspective (Japan Society of Mechanical Engineers, 2013). The focus here is on the content
related to tsunami, and an overview is given.
The proposals comprised four issues: “I. System integration of large systems”, “II. Design-based
approach and addressing the ‘beyond’ ”, “III. Issues pertaining to risk communication”, and “IV.
Continuing research and its development into standards and criteria”.
Issue I points out the presence of weaknesses found in gaps in specialized knowledge about
nuclear power plants and other large facilities, and proposes as a countermeasure that a methodology
for system integration be systematized into the “science of design”.
Issue II points out that a lesson learned is to properly explain to society in advance the risk of any
exceedance in cases where an “estimated value” is set for planning or design of man-made structures
and to obtain society’s acceptance of this risk of exceedance as an “acceptable risk”, and proposes thatsuch procedures be followed in formulating any “estimated values”.
Issue III states the need for accurately predicting the inherent risks and benefits during the
manufacturing planning stage, announcing these risks and benefits to society and obtaining society’s
understanding in advance, as well as the need for risk communication during the preceding stage
beginning with design in issue II. To this end, it is proposed that engineers study the essential
knowledge for PRA standards and other risk management methodologies.
Issue IV proposes continuing research as well as incorporating the results of such investigations

Appendix 1 - 6

and research into standards, criteria, manuals and so on, and, furthermore, developing as well as
training researchers and engineers.
1.1.5. Ministry of Land, Infrastructure, Transport and Tourism
After the 2011 Tohoku earthquake, the Ministry of Land, Infrastructure, Transport and Tourism
compiled the “Guide to Configuring Estimates of Tsunami Inundation” (Ministry of Land,
Infrastructure, Transport and Tourism, 2012), “Guidelines on Tsunami Resistant Design ofBreakwaters” (Ministry of Land, Infrastructure, Transport and Tourism, 2013a), and “Guidelines on
Tsunami Resistant Design of Seawalls (Parapets) in Ports” (Ministry of Land, Infrastructure, Transport
and Tourism, 2013b). These publications each presented the approach of estimating tsunami
inundation along the coast where significant damage was sustained due to the tsunami resulting fromthe 2011 Tohoku earthquake as well as such techniques and their utilization, along with the basic
concepts for tsunami resistant design of breakwaters and seawalls at port facilities.
The first guide assumed the largest class of tsunami and proposed the approach of “protecting
human life no matter what” by minimizing damage through multiple layers of defense comprised ofmany tangible and intangible measures, and detailed such methods. The latter two guidelines took into
consideration the social impact of tsunami on human life, property, etc., and called for the appropriate
setting of contextual safety goals for ports with respect to such facilities and seawalls in keeping withtsunami size and frequency. With respect to both designs, the proposal is for design to be undertaken
in a manner that addresses design-basis tsunami after taking into consideration movements, such as
Level 2 ground motion, as described in the “Technical Standards and Commentaries for Port andHarbour Facilities in Japan” (Ports and Harbours Association of Japan, 2007; English version - The
Overseas Coastal Area Development Institute of Japan, 2009) and to aim for a “resilient structure” tothe extent possible that would not collapse easily even if struck by a tsunami exceeding the designbasis tsunami in order to enhance the effectiveness of structures in minimizing damage. In this way
proposals have been made that aim to minimize damage through multiple layers of defense comprisedof multiple countermeasures as well as the need for a design to counter a tsunami exceeding the design
tsunami after taking into consideration the effects of seismic vibration on facilities that provide
tangible countermeasures, which are one type of countermeasure.
1.1.6. Trends around the World(1) IAEA
In 2011, the IAEA published a detailed safety guide entitled “Meteorological andHydrological Hazards in Site Evaluation for Nuclear Installations” (IAEA, 2011). This

Appendix 1 - 7

publication is a compilation of guidance and recommendations on climate and hydrologicaldisasters striking nuclear power facilities, and addresses tsunami as well as storm surge, windgenerated waves, seiches, floods and other events. In addition, basic approaches tocountermeasures and other concepts are discussed as well as the “dry site” concept as a measure
to counter general flood damage not limited to tsunami.
(2) United States
The United States has experienced damage from tsunami along its Pacific coast. In 2009,
the NRC released “Tsunami Hazard Assessment at Nuclear Power Plant Sites in the United Statesof America (NUREG/CR-6966)” (NRC, 2009). This publication provides an overview ofmethods for assessing tsunami in general. In addition to earthquakes, descriptions are given offactors giving rise to tsunami, including submarine landslides, slope failure and volcanic
phenomena. In addition, descriptions are given of the effects of tsunami on a nuclear power plant,
explaining run-up overflow, descending water levels, scouring, sedimentation, tsunami force,
debris and methods for assessing the effects of these. Furthermore, in 2016 two volumes were
published: “Tsunami Hazard Assessment: Best Modeling Practices and State-of-the-Art
Technology (NUREG/CR-7223)” and “Tsunami Hazard Assessment Based on Wave Generation,
Propagation, and Inundation Modeling for the U.S. East Coast (NUREG/CR-7222)”. The former
is a broad compilation of the latest methods for tsunami assessment, and the latter describes
methods for tsunami assessment along the eastern coast of the United States, including specificexamples. In addition, a probabilistic tsunami hazard analysis was conducted at the Diablo
Canyon Power Plant in the United States (PG&E, 2010). In addition to earthquakes, consideration
was also given to submarine landslides as a factor giving rise to tsunami.
1.2. Future direction and role of this publication
Here, the course taken in research on tsunami countermeasures in Japan is considered in looking
back on close to 20 years of tsunami countermeasures for nuclear power plants, and the role of thispublication is discussed in improving the safety of nuclear power plants in the future.
Research on tsunami countermeasures since the end of World War II has been confirmed since
the late 1950s and early 1960s, and discussed tangible countermeasures by means of structures as wellas intangible countermeasures by means of evacuations and other such methods, ever since suchresearch was first conducted. Later, seawalls and other tangible countermeasures have been
implemented in regions damaged by massive tsunami occurring around the Japan Trench or Nankai
Trough. The tsunami heights estimated when implementing these countermeasures principallyreferenced the heights of historical tsunamis. In the latter 1990s, a shift was proposed from historical

Appendix 1 - 8

tsunami to supposed tsunami for tsunami heights to be used in configuring tsunami countermeasures.
Following this, in 2002, the “Tsunami Assessment Method for Nuclear Power Plants in Japan” wasdeveloped, which compiled methods for evaluating water levels using probable tsunami based onseismological and other knowledge as well as data on historical tsunamis. This method contributed tothe evolution of methods for configuring tsunami water levels for nuclear power plants in Japan. The
massive tsunami resulting from the 2011 Tohoku earthquake significantly exceeded the tsunami
heights configured based on data at the time using this method, and four nuclear power plants,
Onagawa, Fukushima Daiichi, Fukushima Daini and Tokai, experienced inundations of seawater due
to the effects of the tsunami inside their sites or buildings. Of these nuclear power plants, threelocations were successfully shut down safely, but the tsunami caused a situation at the Fukushima
Daiichi Nuclear Power Station where a large quantity of radioactive materials was released.
Following this, the Japan Society of Civil Engineers and other academic societies presented
recommendations from their respective perspectives. As stated in Appendix Sections 1.1.2 to 1.1.4,
what the recommendations presented by the Japan Society of Civil Engineers, JSME and AESJ havein common is the importance they place on countermeasures pertaining to tsunami that exceed design
scale. The Japan Society of Civil Engineers proposes this in terms of “anti-catastrophe” performance,
and the JSME provides proposals in terms of “responding to ‘beyond’ ”. The AESJ states that thepreviously proposed defense in depth should be better understood and its application enhanced. In
addition, the Ministry of Land, Infrastructure, Transport and Tourism has put forth proposals toappropriately configure design tsunami for ports and other structures along coastlines as well as aiming
for a “resilient structure” that increases the effectiveness of minimizing damage even with respect toa tsunami exceeding the design tsunami.
Taking the aforementioned into consideration, it is important that the concept of defense in depth
be kept in mind for natural external forces such a tsunami with respect to nuclear power plants, thatsafety targets be appropriately configured and multiple configurations made of the design scale as wellas on a scale exceeding such settings for natural external forces, and that countermeasures beconstructed commensurate with these respective scales. This will make it possible to maintain the“anti-catastrophe” performance that allows for a “response to address the ‘beyond’” in addition tosafety as concerns external forces in terms of the design scale. The content detailed here is stillconceptual, so it is necessary, in the near future, to specifically systematize this concept by taking into
consideration the special characteristics of nuclear power plants, and it is essential that collaborative
work be conducted in various fields toward this end.
One sort of collaboration with respect to tsunami is the release of the publication “Tsunami
Resistant Engineering for Nuclear Safety”, which was compiled by the Japan Association for
Earthquake Engineering. This publication brings together knowledge of experts in the fields ofearthquake engineering, nuclear engineering, civil engineering and other areas to systematize

Appendix 1 - 9

comprehensive technologies for ensuring the safety of nuclear power plants against tsunami, and it ishoped that this publication will be used and developed in the future.
The elemental technologies pertaining to tsunami assessment compiled in this publication, in
addition to their use in safety assessments and other examinations of nuclear power plants, play animportant role in quantitatively assessing the effects of tsunami, which is necessary for a frameworkfor safety assessments that will be systematized in the future. In addition, it goes without saying that
it is important that the framework for safety assessments and the elemental technologies in thispublication be constantly updated through continuous research and investigation based on the latest
research results and other findings in the endeavor to improve safety.

[Appendix 1 References]
Atomic Energy Society of Japan’s Investigation Committee on the Nuclear Accident at the Fukushima
Daiichi Nuclear Power Plant (2014): Full Picture of the Fukushima Daiichi Nuclear Power
Station Accident and Proposals for Tomorrow: Final Report of the Society’s Accident
Investigation, 448p.
http://dl.hieng.ir/bot/165287498_1488715197.pdf (Accessed on August 2016)
Central Disaster Management Council (2003): The Report of Tonankai and Nankai Earthquake, 50p.
(in Japanese).
http://www.bousai.go.jp/kaigirep/chuobou/9/ (Accessed on April 2016)
Committee on Specific Topics Concerning Civil Engineering Technology for Nuclear Safety (2013):
Proposal on Optimal Aseismicity and Tsunami Resistant Performance of Nuclear Power Plants(Civil Engineering Perspective).
http://committees.jsce.or.jp/2011quake/node/158 (Accessed on April 2016)
Fujii, N., M. Ikeno, T. Sakakiyama, M. Matsuyama, M. Takao and K. Mukaihara (2009): HydraulicExperiment on Flow and Topography Change in Harbor due to Tsunami and Its Numerical
Simulation, Journal of Japan Society of Civil Engineers B2, Vol. 56, pp. 291-295 (in Japanese).
Fujita, N., K. Inagaki, N. Fujii, M. Takao and T. Kaneto (2010): Study on Field Applicability of
Estimation Model for Topography Change due to Tsunamis, Annual Journal of Civil
Engineering in the Ocean, Vol. 26, pp. 213-218 (in Japanese).
Geospatial Information Authority of Japan, Ministry of Agriculture, Fisheries Agency, Ministry ofTransport, Japan Meteorological Agency, Ministry of Construction, and the Fire and Disaster
Management Agency (1998): Guide to Strengthening Tsunami Countermeasures in Regional
Disaster Prevention Plans (in Japanese).
http://tsunami-dl.jp/document/022 (Accessed on August 2016)

Appendix 1 - 10

IAEA (2011): Meteorological and Hydrological Hazards in Site Evaluation for Nuclear Installations,
Draft Safety Guide, DS417, 2011.
http://www-pub.iaea.org/MTCD/publications/PDF/Pub1506_web.pdf(Accessed on August 2016).
Ikeno, M., T. Yoshii, M. Matsuyama and N. Fujii (2009): Calculation of Suspended Sediment Pickup
based on Tsunami Experiments and Proposal of Pickup Equation, Journal of Japan Society of
Civil Engineers B2, Vol. 65, pp. 506-510 (in Japanese).
Japan Electric Association (2008): Nuclear power plant seismic design technical guidelines,
JEAG4601-2008, 222p. (in Japanese).
Japan Society of Civil Engineers, Tsunami Evaluation Subcommittee, Nuclear Civil Engineering
Committee, JSCE (2002): Tsunami Assessment Method for Nuclear Power Plants in Japan,
72p. (in Japanese).
http://committees.jsce.or.jp/ceofnp/node/5 (Accessed on April 2016)
Japan Society of Civil Engineers, Tsunami Evaluation Subcommittee, Nuclear Civil Engineering
Committee (2006): Tsunami Assessment Method for Nuclear Power Plants in Japan, 2006.
http://committees.jsce.or.jp/ceofnp/system/files/JSCE_Tsunami_060519.pdf(Accessed on August 2016)
Japan Society of Civil Engineers, Tsunami Evaluation Subcommittee, Nuclear Civil Engineering
Committee, (2011): Methods for Probabilistic Tsunami Hazard Analysis.
http://committees.jsce.or.jp/ceofnp/node/39 (Accessed on August 2016)
Japan Society of Mechanical Engineers (2013): Lessons Learned from the Great East Japan
Earthquake Disaster, Report of the JSME Research Committee on the Great East Japan
Earthquake Disaster, 122p.
https://www.jsme.or.jp/jsme/uploads/2016/08/Great-East-Japan-Earthquake-Disaster-FullText.pdf (Accessed on August 2016)
Kurita, T., M. Matsuyama, and D. Uchino (2013): Uncertainty of Numerical Tsunami Simulation
Evaluated in Comparison with the Field Survey Results of the 2011 Tohoku Earthquake
Tsunami, Journal of Japan Society of Civil Engineers B2, Vol. 69, No. 2, pp. I-216 - I-220 (inJapanese).
Ministry of Land, Infrastructure, Transport and Tourism (2011): Basic guidelines on promotion oftsunami disaster prevention area (in Japanese).
http://www.mlit.go.jp/common/000188287.pdf (Accessed on August 2016)
Overseas Coastal Area Development Institute of Japan (2009): Technical Standards and Commentaries
for Port and Harbour Facilities in Japan, 998p.
Pacific Gas and Electric Company (2010): Methodology for Probabilistic Tsunami Hazard Analysis:
Trial Application for the Diablo Canyon Power Plant Site, 182p.

Appendix 1 - 11

Ports and Harbours Bureau, Ministry of Land, Infrastructure, Transport and Tourism (2013a):
Tsunami design guidelines for breakwaters, 35p. (in Japanese).
http://www.mlit.go.jp/kowan/kowan_tk5_000018.html (Accessed on August 2016)
Ports and Harbours Bureau, Ministry of Land, Infrastructure, Transport and Tourism (2013b):
Tsunami design guidelines for tsunami wall in harbours, 35p. (in Japanese).
http://www.mlit.go.jp/kowan/kowan_tk5_000018.html (Accessed on August 2016).
Sasaki, S. (1959): Countermeasures against tsunami disaster at Sanriku Coastal Area, Proceedings of
The 6th Coastal Engineering Conference, pp. 18-28 (in Japanese).
U.S. Nuclear Regulatory Commission (2009): Tsunami Hazard Assessment at Nuclear Power Plant
Sites in the United States of America - Final Report (NUREG/CR-6966), 84p.
http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6966/(Accessed on August 2016)
U.S. Nuclear Regulatory Commission (2016a): Tsunami Hazard Assessment Based on Wave
Generation, Propagation, and Inundation Modeling for the U.S. East Coast (NUREG/CR7222), 133p.
https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7222/(Accessed on August 2016)
U.S. Nuclear Regulatory Commission (2016b): Tsunami Hazard Assessment: Best Modeling Practices
and State-of-the-Art Technology (NUREG/CR-7223), 117p.
http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7223/(Accessed on August 2016)

Appendix 1 - 12

Chapter 2. Examination of Tsunami Source Configuration
2.1. Basic matters for tsunami source configuration
2.1.1. Earthquake source region and ground physical properties(1) Initiation location of past earthquakes
Large past tsunamis, which have occurred around Japan, have been concentrated along plateboundaries and the eastern margin of the Japan Sea, and it has been extremely rare for a tsunami
to occur in the East China Sea side of Kyushu or the Japan Sea side of southwestern Japan.
Earthquakes having a magnitude of 9 or greater, which have occurred around the world since the20th century, have initiated in subduction zones. According to Figure 1 in Rajendran (2013), thesource regions of interplate earthquakes of M8.5 or greater, which have occurred between 1906
and 2012, have not overlapped with each other.
(2) Seismogenic layer
Around the Japanese Archipelago, earthquakes have occurred in a variety of patterns, but
the locations where both interplate and intraplate earthquakes occur have been found to be limited.
The region where interplate earthquakes occur along a plate boundary is called the seismogenic
zone, and Pacheco et al. (1993) stated that such a region corresponds to one where stable slip
occurs, and believed that thrust-type (shallow dipping reverse fault-type) earthquakes occurredalong a plate boundary within this region. However, it is known that there is coupling to a certain
extent even near trench axes and deep transition zones, and consideration has also been given to
including these in tsunami source models.
Lay et al. (2012) analyzed differences in behavior in terms of depth along plate boundaries
where megathrust earthquakes have occurred in order to explain differences in the characteristics
of seismic wave radiation between large and medium-sized earthquakes. After classifying theinclination of the dip angle into four regions, the authors presumed the rupture domains of large
earthquakes in recent years as shown in Table 2.1.1-1 based on their analyses of tsunami andseismic waves.
Even when looking at inland crustal earthquakes, it has been pointed out that there is aseismogenic layer where failure does not progress beyond a specific depth. The cause of thislower limit to the seismogenic layer is believed to be because the rupture pattern in rock changes
due to temperature and pressure, in other words due to depth (Ito, 2008). Consequently, whenearthquakes are greater than a specific magnitude, fault width reaches a maximum.
The thickness of this seismogenic layer varies depending upon location.

Appendix 2 - 1

Table 2.1.1-1 Rupture domains of interplate megathrust faults (Lay et al., 2012)
DomainRupture Characteristics• From the trench down to about 15 km depth below sea
level• Either aseismic deformation or large coseismic

A - near trench domain

displacements in tsunami earthquakes• Tsunami earthquakes or anelastic deformation and stablesliding occur• From 15 to 35 km depth

B - central megathrustdomain• Large slip occurs with minor short-period seismic
radiation• From 35 to 55 km depth

C - downdip domain• Moderate slip occurs with significant coherent shortperiod seismic radiation• Depth of 30-45 km in several subduction zones, typicallyinvolving subduction of relatively young plates with

D - transition domain

shallow dip angles• Slow slip events, low frequency earthquakes (LFEs), andseismic tremor can occur(3) Rigidity modulus of medium near hypocenters
When data for P wave velocity structure and the velocity ratio between P waves and S waves
are used to estimate rigidity corresponding to location and depth, the results given in Table 2.1.12 have been found.
Of these, in cases where “the fault plane covers depths both shallower and deeper than 20km”, it is also possible to take into account the distribution of seismic moment to calculate rigidity
in cases where a seismic model is used that takes into account slip heterogeneity.
Crust 1.0 (Laske et al., 2013) is a data set of crustal structures around the globe.

Appendix 2 - 2

Table 2.1.1-2 Rigidity modulus of medium near hypocenters
RegionBasis

Intraplate region in southwest Japan, theAdopt the intermediate value of theeastern margin of the Japan Sea, andrange below:

shallow plate boundary (when the entire

Vp=6.0km/s

fault plane exists at a depth of 20 km or

Vp/Vs=1.6-1.7

less)

ρ=2.7-2.8g/cm3

Rigidity modulus

3.5×1010 N/m2
(3.5×1011 dyne/cm2)

lead toμ=3.36×1010-3.94×1010 N/m2
Intraplate region of oceanic plate, and deep

Adopt the intermediate value of theplate boundary (when the entire fault plane

range below:

exists at a depth of 20 km or more)

Vp=8.0-8.1km/s
Vp/Vs=1.75-1.80
ρ=3.2-3.5g/cm3

7.0×1010 N/m2
(7.0×1011 dyne/cm2)

lead toμ=6.31×1010-7.50×1010 N/m2
Medium depth of plate boundary(fault
plane covers depths both shallower anddeeper than 20 km)

Adopt intermediate values between
shallow and deep regions

5.0×1010 N/m2
(5.0×1011 dyne/cm2)(4) Plate relative motion and boundary shape
In Figure 2.1.1-1, general values are given based on Seno (2005) for the relative movement
velocity of plates around the Japan Archipelago. In addition to this, Loveless and Meade (2010)
calculated the relative movement of blocks subdividing the area around the Japan Archipelago.
Both of these are generally consistent with each other.
Bird (2003) proposed a model for plate relative movement around the world (PB2002),
dividing plate boundaries according to type. The areas between the Kuril-Kamchatka Trench andJapan Trench, Nankai Trough and Ryukyu Trench as well as the Izu-Ogasawara Trench have been
divided into subduction zones (SUB). The eastern margin of the Japan Sea is regarded as an
oceanic convergent boundary (OCB), and, although there is a converging boundary, it isdistinguished from a subduction zone. The definitions of these two types are given in Table 2.1.13.

Appendix 2 - 3

North American Plate

Okhotsk
Plate
Eurasian Plate

Philippine Sea
Plate

Pacific Plate(Unit: mm/year)
Figure 2.1.1-1 Approximate value of plate relative motion velocity around the Japanese archipelago(Seno, 2005 ©Tokyo Geographical Society)
Table 2.1.1-3 Classification condition of plate boundary type SUB and OCB (Bird, 2003)
Class

Condition• Plate boundary steps with a convergent (component of ) velocity

SUB• Having a Benioff zone of intermediate to deep earthquakes and/or a parallel
volcanic arc with Quaternary activity• Lying entirely within seafloor whose age is known from linear magnetic

OCB

anomalies to be less than 180 Ma, and/or at water depths exceeding 2000 m• Relative velocity has an azimuth above ±20 deg. of the azimuth of the plateboundary step

In order to create models of tsunami sources based on interplate earthquakes, data on depth
distribution along plate boundaries are necessary. In addition to various references concerning
plate boundary shape, the following available sources provide such data.
• National Research Institute for Earth Science and Disaster Resilience: Japan Seismic
Hazard Information Station (J-SHIS)
http://www.j-shis.bosai.go.jp/• United States Geological Survey (USGS): Slab Models for Subduction Zones
http://earthquake.usgs.gov/data/slab/• Headquarters for Earthquake Research Promotion, Earthquake Research Committee(2004): Long-Term Assessment of Seismicity Around the Sea of Hyuganada and theSouthwest Islands Trench

Appendix 2 - 4

• Ministry of Education, Culture, Sports, Science and Technology’s Research andDevelopment Bureau and the Japan Agency for Marine-Earth Science and Technology(2013): Project for Assessment and Research on Multi-Segment Ruptures in Eastern Sea,
Southeastern Sea and South Sea Earthquakes: Report of Survey, Observation and Research
Results to Assess Multi-Segment Ruptures in Eastern Sea, Southeastern Sea and South Sea
Earthquakes (2008~2012)• Cabinet Office (2012): Investigative Commission on Models of Megathrust Earthquakes
in the Nankai Trough (Second Report)(5) Interplate coupling and earthquake magnitude
In recent years, supercycle earthquakes (Sieh et al., 2008) have been suggested, which arethought to occur in inherent periods longer than the periods of time for which information has
been obtained from archives and mechanical records.
Nishimura (2012a) has aligned plate boundaries where strong coupling has been estimatedbased upon geodetic observations and areas where megathrust earthquakes have occurred sincethe 20th century. Moreover, the current state of knowledge taking into account advances made ingeodetic interplate coupling research has been compiled below.
• Mean degree of coupling specific to a subduction zone
 Large: Cascade, Chile, Sumatra and Nankai Trough Medium: Kamchatka, Aleutian, Alaska, Mexico, Central America, Colombia, Peru
and Japan Trough Small: Subduction zones in the Western Pacific (New Zealand, Tonga, IzuOgasawara, Mariana, etc.)• Source regions of megathrust earthquakes (moment magnitude (“MW”) up to 9), whichhave occurred in the past, have been estimated to have coupling ranging from medium tostrong, and they do not uniformly have a strong coupling. Megathrust earthquakes are
unknown in subduction zones where coupling is estimated to be weak.
• The breadth of coupling regions (including partial coupling) ranges up to a maximum of
300 km. The occurrence of megathrust earthquakes is known in Chile, Alaska and theJapan Trough, which all have coupling of a larger scale.
• There are also many subduction zones, such as the Aleutians and other areas, where there
is a significant change in the degree of coupling in the strike direction of the subduction
zone.
• Although it is difficult to explain interplate coupling in terms of single parameters such asplate relative velocity or the date of the subducting plate, attempts to explain the existenceof any degree of coupling have been effective when multiple elements are combined (seeAppendix 2 - 5

for example Scholz and Campos, 1995).
Scholz and Campos (1995), which has been mentioned in this context, has been updated by
Scholz and Campos (2012). Scholz and Campos (2012) estimates seismological interplate
coupling based upon earthquake history and geodetic interplate coupling based upon GPS data,
and finds that, excluding a small number of exceptions, both coincide with a difference of lessthan 10%. Based on this, the coupling coefficient for Honshu (along the Japan Trench) is
0.54~0.65, 1.0 for the Nankai Trough and 0 for the Ryukyu trench, and there is a connection
between the coupling coefficient and the force in a normal direction acting between the plates.
Wang and Bilek (2014) presented the following views regarding the relationship between
plate boundary surface shape and earthquake magnitude.
• All observed megathrust earthquakes have occurred in sea regions where smooth
topography has been subducting. Plate boundaries accompanied by topography, where
there is very significant undulation, creeps, and megathrust earthquakes have not occurredin such areas.
• Subducting seamounts are typical examples of terrain with significant undulation. Regions
where seamounts are subducting are accompanied by medium to small earthquakes, andno evidence has been obtained that large earthquakes have occurred. The termination on
the southern end of the fracture of 2011 Tohoku earthquake (the 2011 off the Pacific coastof the Tohoku Earthquake) occurred not at a location where the Philippine Plate was thefoot wall, but in an area where seamounts were subducting.
2.1.2. Scaling law and stress drop
(1) Scaling law for earthquake magnitude
As shown in main volume 4.2.1.1 of the main text, there are at least three approaches, which
are described below, with respect to the scaling law for fault parameters related to MW.
1) Method where limits are not set on fault length L, fault width W or slip amount D
log M0 (N·m) = 1.5 MW + 9.1, M0 = μLDW
M0: Seismic moment, μ: Rigidity of medium around hypocenter,
L: Fault length, W: Fault width, D: Slip amountSo, if MW increases by 0.1, then M0 will be 100.15. In cases where no limit is set for either
L, W, or D, if MW increases by 0.1, then L, W, and D will all be 100.05=1.12.

Appendix 2 - 6

2) Method setting a limit only on fault width W (L model)
When W reaches the upper limit, if MW increases by 0.1, then both L and D will be
0.075

10

=1.19.

3) Method setting a limit on mean slip amount D and fault width W (W model)
When D or W reaches the upper limit, if MW increases by 0.1, then both L will be
0.15

10

=1.41.

These three relationships correspond to the scaling laws for the three stages presented by
Irikura and Miyake (2011) and Murotani et al. (2015), which will be discussed later. According
to the scaling laws for the three stages, as the fault length increases, there is a shift in therelationship from 1)->2)->3). 3) is a state where slip amount is saturated with respect to fault
length and has been substantiated by a variety of data in recent years.
(2) Static stress drop
The extent of the release in stress before and after fault motion is referred to as stress drop.
In particular, the difference in shear stress prior to fault motion beginning and after its completionis called static stress drop. Because static stress drop corresponds to slip amount per characteristic
length that is targeted, the greater the static stress drops, the greater the slip amount per fault
length and fault area is.
In accordance with the underlying assumptions, static stress drop is expressed according tovarious methods as shown below. In the configuration of fault parameters for a tsunami, theformula for circular faults put forth by Eshelby (1957) is often used unless the link in comparison
to fault with is particularly long and massive.

Δσ=(7/16) M0/(S/π)1.5
where, Δσ: Stress drop, M0: Seismic moment, S: Fault area.
This results in a relationship where mean slip amount D is proportional to S0.5, and, of therelationships discussed in main volume 4.2.1.1 of the main volume, this corresponds to “1)
Method where limits are not set on fault length L, fault width W or slip amount D”.
(3) Knowledge about stress drop and scaling laws as concerns interplate earthquakes
Murotani et al. (2013) analyzed fault models for interplate earthquakes around the world,and proposed the following scaling law for MW =6.7 ~ 9.2 earthquakes.
S=1.34×10-10M02/3
D=1.66×10-7M01/3
Sa=2.81×10-11M02/3=0.2S
where, S refers to the fault area (km2), M0 seismic moment (N·m), D mean slip amount (m), andAppendix 2 - 7

Sa the asperity area. When rigidity is calculated using the above formula, it is found to be
μ=4.5×1010(N/m2), and stress drop according to the formula for circular fracture surface isΔσ=1.57(MPa). When standard deviation is taken into consideration for the parameters, stressdrop is within a range of 1.57/1.91=0.82~1.57×1.91=3.00 (MPa), which is almost equivalent to
the range of MW ±0.2. Moreover, the range of 0.5×standard deviation for stress drop according to
Murotani et al. (2013) is 1.57/1.910.5=1.14~1.57×1.910.5=2.17 (MPa), which is almost equivalent
to the range of MW ±0.1.
The Cabinet Office (2012) analyzed fault models for six case studies of trench-type
megathrust earthquakes around the world and found that the value for mean stress drop was
1.2MPa, and the value adding standard deviation to the mean value was 2.2MPa, and the value
subtracting standard deviation from the mean value was 0.7MPa. Moreover, when earthquakes
smaller than MW=8.0 are included, taking into account that the value of the mean stress drop fortrench-type earthquakes is 3.0MPa and that 3.0MPa was used for the mean stress drop in theCentral Disaster Management Council’s review of tsunami associated with trench-type
earthquakes, this has been applied to the principle fault for megathrust earthquakes in the Nankai
Trough (areas that are deeper than the 10 km depth of the plate boundary surface).
This stress drop of 3.0 MPa has often been used in recent years as the stress drop forinterplate earthquakes viewed conservatively. However, even when viewed from the relationshipdescribed by Murotani et al. (2013), it is the maximum stress drop within the scope of standard
deviation for the parameters.
(4) Heterogeneity of slip amount distribution on fault planes
It is known that fault motion during an earthquake is not uniform and that there are
significant localized areas of slip amount on fault surfaces. Somerville et al. (1999) statisticallyanalyzed source parameters for 15 intraplate earthquakes that occurred between 1971 and 1995,
and obtained the scaling laws shown in Table 2.1.2-1. This relationship has been used as thestandard for heterogeneous models with regard to strong motion prediction. The heterogeneity ofthis fault motion also affects tsunami. Since Satake (1989), research has been conducted to findthe heterogeneity of fault motion using inversion of the tsunami shape. With this method, thefault plane is subdivided into several small faults, and the calculation tsunami shape at theobservation point when unit slip amount is given for each of these is regarded as Green’s function.
The least-square method is used to determine weighting (slip amount of each small fault) so thatthe superposition weighted to each Green’s function conforms to the observed tsunami shape.
Annaka et al. (1999) proposed a method that introduces run-up height records of tsunami into theevaluation function and reflects nonlinearity in shallow sea areas. In cases where the size of the

Appendix 2 - 8

fault studied is large, a method has also been used where the time variation of displacement foreach small fault is included in the inversion object (see for example Satake et al., 2013).
For the tsunami source models for probable maximum tsunamis that reflect heterogeneity inslip distribution, the characteristic models indicated in appendix volume 2.2 and 2.3 have often
been used, but methods have also been proposed that represent slip distribution more randomly.
These are based on the method for preparing random source models proposed by Mai and Beroza(2002), and, by deploying slip distribution and other elements on fault planes into wavenumber
regions and setting the correlation distance, complex tsunami source models have been preparedthat have patches for large slip with respect to large earthquakes. Goda et al. (2014) and Fukutani
et al. (2015) applied this to tsunami having their source along the Japan Trench, and Yasuda et al.
(2015) to tsunami associated with the Nankai Trough to assess the impact that uncertainty in slip
distribution has on tsunami water levels.
Table 2.1.2-1 Scaling laws for heterogeneous source models (Somerville et al., 1999)
Rupture Area vs. Seismic Moment

𝐴 km

Average Slip vs. Seismic Moment

2.23

𝐷 cm

Combined Area of Asperities vs. Seismic Moment
Area of Largest Asperity vs. Seismic Moment
Radius of Largest Asperity vs. Seismic Moment𝑀dyne cmdyne ⋅ cm
𝑑yne ⋅ cm

10

𝑀

⁄

dyne ⋅ cm

1.08

10

𝑀

⁄

dyne ⋅ cm

𝑅 km

1.35

10

𝑀

⁄

dyne ⋅ cm

𝑇 sec

2.03

10

𝑀

⁄

dyne ⋅ cm

5.00

𝐴 km

3.64

𝑟 km

Area of Fault Covered by Asperities

0.22

Average Asperity Slip Contrast

2.01

Slip Duration vs. Seismic Moment

10

⁄

𝑀

𝐴 km

2.6

Asperity vs. Moment

𝑀⁄

Average Number of Asperities

Hypocentral Distance to Center of Closest

1.56

⁄

10
10

Corner Spatial Wavenumber Along Strike

log 𝐾 𝐶 km

1.72

0.5𝑀

Corner Spatial Wavenumber Down Dip

log 𝐾 𝐶 km

1.93

0.5𝑀

*Units added to Somerville et al. (1999)
2.2. Earthquakes supposed along plate boundaries
2.2.1. Knowledge gained from 2011 Tohoku earthquake
Here, points are deduced and consolidated from knowledge about 2011 Tohoku earthquake that
may serve as reference for methods of configuring probable maximum tsunami.

Appendix 2 - 9

(1) Earthquake magnitude and fracture zone expansion
Of the regional divisions shown in Figure 2.2.1-1, significant slip was observed during 2011
Tohoku earthquake in regions along the trench in the southern area off the coast of Sanriku andalong the trench off the coast of Boso from the northern area off the coast of Sanriku. The regions
off the coast of Ibariki Prefecture, off the coast of Fukushima Prefecture, off the coast of Miyagi
Prefecture and in the central area off the coast of Sanriku have also been regarded as source
regions. The earthquake magnitude, which was MW=9.0, and the breadth of the fracture zone
(length of approximately 450 km and width of approximately 200 km) significantly exceeded
what had previously been assumed. The following points have been cited as distinguishingfeatures of this earthquake.
• Rupture occurred that extended across the typical interplate thrust earthquake region andtsunami earthquake region near trench axes.
• Rupture extended to the region near trench axis where it had not been known that tsunami
earthquakes had occurred in the past.
• Significant deviation was seen in slip amount in both the strike direction and dip angle
direction.

A: North Sanriku-Oki
B: Central Sanriku-Oki

A

C: Miyagi-Oki
D: South Sanriku-Oki

B

E: Fukushima-Oki

H

F: Ibaraki-Oki

CD

G: Boso-Oki
E

H: Region close to the axis of JapanF

TrenchG

Figure 2.2.1-1 Segmentation of seismic activity area from Sanriku-Oki to Boso-Oki (HERP, 2011)(2) Significant slip near trench axes
It has commonly been estimated, using multiple methods, that approximately a slip of 50
meters occurred near the trench axis. The model, which was prepared by the Geospatial

Appendix 2 - 10

Information Authority of Japan and Japan Coast Guard (2011) that reproduces crustal movements
is shown in Figure 2.2.1-2, and indicates that there is a maximum of approximately 56 meters ofslip amount.

Data : F3 final solution of GNSS by GSI(fixed point is 'Fukue' in Kyushu) and seafloor
geodetic observation (SGO) data by JCG
Period : From March 10th to March 12th, 2011.
The star shows the epicenter location of the main shock. The moment magnitude is 9.0 whenrigidity modulus is assumed to be 40 GPa. The dashed lines show depth of the plate boundary.
The vectors show slip distribution on the plate boundary.
Figure 2.2.1-2 Slip amount distribution of 2011 Tohoku earthquake to explain ground and seafloor
crustal movements (Geospatial Information Authority of Japan and Japan Coast Guard,
2011)

Appendix 2 - 11

(3) Analysis of cumulative stress
It has been pointed out that accumulated strain was released over a broad range across theregion where 2011 Tohoku earthquake initiated. Also, it has been pointed out that near trenchaxes where coupling had conventionally been regarded as very small, there is the possibility ofstress accumulation and coupling to a certain extent.
Hasegawa et al. (2012) stated that the strain, which had accumulated across a range
extending from the central area off the coast of Sanriku to off the coast of Fukushima, almost
completely released due to the change in the stress state before and after 2011 Tohoku earthquake
occurred. The Japan Agency for Marine-Earth Science and Technology (2013), based on borehole
surveys conducted by the Agency’s Deep-sea Drilling Vessel Chikyu, found that the stress statein the source region of the Pacific coast of the Tohoku region changed from a compressed state
to an expanded one.
(4) Data acquired prior to the earthquake and response to phenomena during the earthquake
According to Zhao et al. (2011), the large slip area during 2011 Tohoku earthquake
corresponded to the high velocity region along the plate boundary. Also, the high velocity region
formed asperity where there was significant coupling between plates corresponding to subductionof seamounts and other features, and, in this region, the core of the megathrust earthquake formed
due to the accumulation of stress over a long period of time.
According to Nishimura (2012b), the region of significant slip during the earthquake
generally corresponds to places where there was considerable slip deficit as estimated based on
GPS data prior to the earthquake. However, the distribution of slip deficit changed over time dueto the impact of postseismic deformation and other effects. Koketsu et al. (2012) stated that
regions where there was significant back slip were related to the cycle of megathrust earthquakes.
Based on such knowledge, it is possible that regions where significant stress dissipates
during an earthquake may be related using information obtained in between earthquake strikes.
(5) Time variation of the rupture
Using tsunami shape inversion, it has been found that an interplate earthquake (MW=8.8)
such as that of the Jogan earthquake model serves as a trigger for tsunami earthquakes such asthat experienced in 1896 (Satake et al., 2012). According to Satake et al. (2013), slip up to a
maximum of 25 meters occurred within 2.5 minutes after fracture initiated in the depths of theplate boundary off the coast of Miyagi Prefecture. Also, near trench axes, slip up to a maximumof 69 meters occurred 3 to 4 minutes after fracture initiated. Moreover, near the trench axis off
the coast of Sanriku, slip measuring 10 meters occurred around 4 minutes after fracture initiated.
Whether or not consideration is given to such time delays results in differences in tsunami shape.

Appendix 2 - 12

With such a megathrust earthquake, the fracture zone is broad, so consideration needs to be given
to the development of fracture over time in order to reproduce phenomena.
For earthquakes off the Pacific coast of the Tohoku region which have significant slip
amount, tsunami inversion has provided solutions of several minutes for rise time.
Based on the earthquake ground motion data, it has been estimated rise time has been around
30 seconds, which is longer than that for an ordinary M7 class earthquake (several seconds). The
rise times estimated using tsunami and earthquake inversion are given below.
• Tsunami (solution for individual small faults)
 Satake et al. (2013): 30 ~ 150 seconds*Based on inversion where the time windows are 30sec × 5.
 Japan Nuclear Energy Safety Organization (2011): 60 ~ 300 seconds• Earthquake ground motion
 Inversion of high frequency GPS data: Rise time in regions where there is 40~60 mof slip amount is 30~40 seconds, and there is not much correlation with fracture
propagation velocity (Yue and Lay, 2011).
 Reproduction of earthquake ground motion: Rise time of 20 ~ 30 seconds (Kawabe
and Kamae, 2012)
In assessments of strong motion, it is often assumed that rise time ≃ fault width/(fracture
propagation velocity × 2) (see for example the Headquarters for Earthquake Research Promotion,2009). When based on this assumption, then:If rupture propagation velocity is 2.8km/s and fault width is 50km, then rise time willbe 8.9 seconds
If rupture propagation velocity is 2.8km/s and fault width is 100km, then rise time willbe 17.9 seconds.
From this, it may be seen that there are cases where the rise time found based on the simple
relationship between rupture propagation velocity and fault width and the actual rise time deviate.
(6) Contribution of horizontal crustal movement to tsunami generation
Satake et al. (2013) stated that, because the slope of sea bottom was steep around the trenchaxis, the wave making effect resulting from horizontal crustal movement affects tsunami
amplitude, and the wave making effect resulting from horizontal crustal movement increases the
maximum amplitude of tsunami by 30 to 60%, and approximately 20 to 40% of this maximum
amplitude was a contribution resulting from horizontal crustal movement. Accordingly, neartrenches where the slope of sea bottom is large and the dip angle of the fault is small, the wave
generation effect resulting from horizontal crustal movement may not be disregarded. The wave

Appendix 2 - 13generation effect produced by horizontal crustal movement may be considered using the method
proposed by Tanioka and Satake (1996) (see Section 6.1.2.2 of the main volume).
2.2.2. Region-specific features of tsunami sources (sea areas associated with subduction of the Pacificplate)(1) Sea area along the Kuril-Kamchatka Trench
Figure 2.2.2-1 by the Central Disaster Management Council (2006) shows the tsunami
source region in the northern area extending from the Kuril-Kamchatka Trench to the Japan
Trench. In the sea area along the Kuril-Kamchatka Trench, earthquakes occur continuously anduniformly along the trench as shown in Figure 2.2.2-2, and the segment divisions arecomparatively distinct, and earthquakes have occurred at relatively short intervals. Based ontsunami inversion, it has been found that the Kuril earthquake that occurred in 1918 corresponds
to the previous earthquake in 2006 (Ministry of Education, Culture, Sports, Science andTechnology’s Research and Development Bureau and the Hokkaido University Graduate Schoolof Science, 2012).
Most of the past large earthquakes have been interplate earthquakes, but reverse fault
earthquakes within plates have also occurred such as the 1994 earthquake off the eastern side of
Hokkaido.
In addition, the Central Disaster Management Council (2006) has confirmed, based on the
results of tsunami deposit surveys from the Nemuro to Tokachi regions in Hokkaido, that massive
tsunamis have occurred dozens of times over the past approximately 6,500 years. The earthquakes
corresponding to tsunami deposits at intervals of approximately 500 years are called “500-year
interval earthquakes”, and are believed to be interplate earthquakes that have occurred repeatedly
across the region extending from off the coast of Nemuro to off the coast of Tokachi, with themost recent occurrence in the early 17th century. With regard to tsunami source models for recreating the area flooded, the Central Disaster Management Council (2006) assessed the moment
magnitude at MW=8.6, and Ioki and Tanioka (2016) used additional data to assess the moment
magnitude at MW=8.8. According to the slip deficit distribution which the Geospatial Information
Authority of Japan (2012) estimated using GNSS data, relatively strong coupling has been
observed off the coast of both Kushiro and Nemuro.

Appendix 2 - 14

Etorofu-Oki
Nemuro / Kushiro-oki

Shikotan-Oki

Tokachi /Kushiro-oki
500-year intervals
Northern Sanriku-oki
Meiji Sanriku Type

Miyagi-ken-oki

Figure 2.2.2-1 Map of tsunamigenic zones along the Kuril Trench - the northern area along the Japan
Trench (Central Disaster Management Council, 2006)

Figure 2.2.2-2 Source regions of the large earthquakes along the Kuril Trench (HERP, 2004)

Appendix 2 - 15

According to DeMets (1992) the area from the Bussol Strait to the southeastern part of
Hokkaido forms a forearc sliver and is believed to move in a rotating motion in comparison to
the surrounding area. Both Liu et al. (2013) and the Ministry of Education, Culture, Sports,
Science and Technology (2008) suggested, based on the relationship between regions where
earthquakes have occurred in the past and a three-dimensional crustal heterogeneous structure of
the area where the island arcs meet of the Japan Trench and the Kuril-Kamchatka Trench
produced using seismic wave tomography, that the low velocity region corresponding tospallation of the lower crust in the Hidaka collision zone serves as a fracture barrier. Kasahara etal. (1997) confirmed that, in the region off the coast of the southern Kuril Islands, there aretectonic lines known as the Nosappu fracture zone and the Iturup fracture zone, and that there isa distinguishing feature along these boundaries as the geomagnetic linear sequence and normal
fault systems differ. Also, because the sediment thickness differs on both sides and discontinuity
in the underground structures is seen in the Nosappu fracture zone, these are regarded as factors
resulting in the structure of this ancient oceanic plate dominating the current seismicity barrier.
(2) Region close to the axis of Japan Trench
In the vicinity of the Japan Trench, 2011 Tohoku earthquake occurred as well as tsunami
earthquakes, such as the 1896 Meiji Sanriku tsunami, and intraplate normal fault earthquakes,
such as the 1933 Showa Sanriku tsunami. Aida (1977) proposed a normal fault earthquake modelfor the 1611 Keicho Sanriku tsunami, but Tsuji (1994), Watanabe (1998) and the Headquarters
for Earthquake Research Promotion (2011) indicated the possibility that this was a tsunami
earthquake.
Off the coast of Miyagi Prefecture in the southern area along the Japan Trench, there are
earthquakes that have occurred in areas very close to the land (e.g. the 1978 earthquake off thecoast of Miyagi Prefecture) and earthquakes that have occurred offshore (e.g. the 1897 earthquake
off the coast of Miyagi Prefecture).
A series of earthquakes that occurred off the eastern side (off the coast of Shioya) of
Fukushima Prefecture in 1938 are the only large earthquakes recorded off the coast of Fukushima
Prefecture. In these earthquakes, there were reverse fault earthquakes as well as normal fault
earthquakes. Off the coast of the Boso Peninsula, the 1677 earthquake tsunami occurred, which
is believed to have been a tsunami earthquake in the vicinity of the Japan Trench.
Ye et al. (2012) reported that, in the depths along the plate boundary in the central area off
the coast of Sanriku, there is a low seismicity region where strain is released by aseismic slip
(SLSR: Sanriku-oki low seismicity region), and that the SLSR corresponds to the northern limitof the large slip of 2011 Tohoku earthquake. Also, Uchida and Matsuzawa (2011) showed that
coupling was weak in the depths of the plate boundary in the central area off the coast of Sanriku

Appendix 2 - 16based on an analysis of coupling rates in the source region of 2011 Tohoku earthquake using dataon small repetitive earthquakes.
Off the coast of the Boso Peninsula, from the vicinity of Mito into a southeasterly direction,
the Northeast edge of the Philippine Plate abuts the Pacific Plate. According to the Japan Agency
for Marine-Earth Science and Technology (2011) and Shinohara et al. (2011), propagation of thefracture of 2011 Tohoku earthquake to the south stopped in the region where the plate on the
subducting Pacific Plate changes from the North American Plate to the Philippine Plate.
Based on a numerical simulation of the relationship between the extent of flooding onto the
Sendai and Ishinomaki plains and the extent of flooding estimated from surveys of tsunami
deposits, Satake et al. (2013) stated that there is a high possibility that the 869 Jogan earthquake
was not solely a tsunami earthquake. The Headquarters for Earthquake Research Promotion(2011) found that Jogan earthquakes have recurrence intervals of approximately 600 years,
including the earthquakes similar to 2011 Tohoku earthquake.
Namegaya and Satake (2012) estimated the moment magnitude of the Jogan earthquake at
8.7 if the ratio between the tsunami inundation distance and the tsunami deposit distribution,
which were obtained from 2011 Tohoku earthquake, were factored in, and the inundation range
during the Jogan earthquake was broader than the distribution range of tsunami deposits.
Sugawara et al. (2013) compared the area of the Sendai plain flooded by the 869 tsunami and2011 Tohoku tsunami, and showed that both overlapped for the most part.
(3) Sea area along the Izu-Ogasawara Trench
In the area ranging from the Izu-Ogasawara Trench to the Mariana Trench, no earthquakes
have occurred which have been accompanied by noteworthy tsunami. Near the point where there
is a triple junction of plates, an earthquake off the coast of the Boso Peninsula occurred in 1953,
and, south of there, an earthquake in the waters close to Hachijo Island occurred in 1972. The
earthquake that occurred off the coast of Saipan in 1990 (MW=7.4) and the one in the waters near
Chichijima (Peel Island) in 2010 (MW=7.4) were both intraplate normal fault earthquakes. A
classification of interaction between plates worked out by Abe (1978) placed the sea area ranging
from Izu to the Mariana trench as a stable type in which few earthquakes occur.
Okal et al. (2013) used ISC seismic time series data and WWSSN data to determine thesources and mechanisms for the period during which there are no CMT catalogs (which became
available after 1976). Based on this, it was estimated that, an M8 inter-plate thrust fault
earthquake has occurred once in every 320 years in this sea area.
Fujioka et al. (2002) indicated the geological regional division of the Izu-Ogasawara Trench
partitioned according to tectonic lines.

Appendix 2 - 17

2.2.3. Region-specific features of tsunami sources (sea area associated with subduction of thePhilippine Plate)(1) Sea area along the Sagami TroughIn the northwestern part of Sagami Bay, relatively large tsunamis have occurred incomparison to earthquake magnitudes. The Central Disaster Management Council (2013) foundthat M8 class earthquakes occurring on the upper surface of the Philippine Plate along the Sagami
Trough are believed to have occurred every 200 to 400 years, and, of these, earthquakes
equivalent to or greater than the 1703 Genroku earthquake, which caused significant upheaval on
the edge of the Boso Peninsula, have occurred at intervals between 2,000 and 3,000 years.
The Central Disaster Management Council (2013) conducted an inversion analysis using
crustal movements and tsunami heights from the 1703 Genroku earthquake and the 1923 Kanto
earthquake to create a fault model that takes into account slip heterogeneity. As for earthquake
magnitude, the 1703 Genroku earthquake was MW=8.5 and the 1923 Kanto earthquake MW=8.2.
(2) Sea area along the Nankai TroughIn the sea area along the Nankai Trough, large earthquakes have repeatedly occurred, andthe average recurrence interval has been between 120 and 160 years. The history of theseearthquake occurrences may be explained using a time-predictable model.
In the sea area along the Nankai Trough, the division of fault segments is clear. Althoughcombinations of these segments have changed depending upon the earthquake, they haveoccurred in the Tonankai and Nankaido during almost the same period of time. The pattern ofoccurrence has been that Tonankai occurs first, then Nankaido occurs.
The Headquarters for Earthquake Research Promotion (2013) showed that the pattern withwhich these anticipated earthquakes have occurred is as shown in Figure 2.2.3-1. The Cabinet
Office (2012) applied a fracture propagation velocity of 2.5 km/s and a rise time of 60 seconds
to a model for megathrust earthquakes along the Nankai Trough.

Appendix 2 - 18

D epth

P atterns in
w hich the
T okaiandN ankairegions
interlockP atterns in
w hich tw oearthquakes in theT okai/N ankaiarea
occur w ith
tim e lag

M W based on a

E stim ated rupture area
Z

A

B

C

D

E

scaling law

S hallow
M edium
D eep

8.8

S hallow
M ediumD eep

9.0 *1

S hallow
M edium
D eep

9.0

S hallow
M edium
D eep

9.1 *2

S hallow
M edium
D eep

8.7

S hallow
M edium
D eep

8.9

S hallow
M edium
D eep

8.8

S hallow
M edium
D eep

9.0

S hallow
M edium
D eep

8.7

S hallow
M edium
D eep

8.9

S hallow
M edium
D eep

8.4

S hallow
M edium
D eep

8.7,8.3

S hallow
M edium
D eep

8.5,8.3

S hallow
M edium
D eep

8.7,8.2

S hallow
M edium
D eep

8.5,8.2

E
D
B

C

A
Z

*1：C abinet O ffice (2011) S trong ground m otion m odel
*2：C abinet O ffice (2011) T sunam isim ulation m odel

Figure 2.2.3-1. Patterns of supposed earthquakes along the Nankai Trough (HERP, 2013)(3) Sea area along the Ryukyu Trench
Large earthquakes have repeatedly occurred in the Sea of Hyuganada. Moreover, thedistribution of sources of past tsunamis in the area around Nansei Islands to the south is shownin Figure 2.2.3-2. Kato (1987) reported that the 1771 Yaeyama tsunami caused the significant
run-up height of more than 25 meters on Ishigaki Island. As for the cause, Matsumoto and Kimura(1993) pointed out the existence of large depressed geological formations, which were foundbased upon precise geological surveys and sonic profiling surveys, and indicated the possibilityof submarine landslide occurring due to an earthquake. Nakamura (2009) reported that this could
be explained in terms of a reverse fault earthquake where the fault width was less than 50 km,
and stated that the event was a tsunami earthquake with MW=8.0.

Appendix 2 - 19

According to Goto et al. (2010) as well as Goto and Shimabukuro (2012), there are tsunami
rocks and ancient documents which contains records of tsunami in the southern area. On the other
hand, currently, no records have been discovered with respect to the northern to central areas,
which range from the Okinawa Islands to the Amami Islands. Taking such data into account, theauthors reported that there is a distinctive difference between both areas.

Figure 2.2.3-2 Source distribution of past tsunamis around Nansei Islands occurred after 1664 (Hatori,
1988)*Numbers beside the tsunami source regions are the occurrence date, MJMA, and m of
Imamura and Iida scale.

In the northern area of the Ryukyu Trench, there is a relative displacement where the upper
layer moves toward the sea area, and it has been suggested that the degree of coupling is low
compared to that of the sea area along the Nankai Trough. Yamamoto et al. (2013) reported that
the Kyushu-Palau ridge (KPR) corresponds to an area of distinctly low velocity in the depths of
the Philippine Plate. The 1968 Sea of Hyuganada earthquake and the 1707 Hoei earthquake did
not extend to the KPR, so it is possible that the KPR forms a barrier to fracture propagation during
earthquakes. As for this interpretation, Wallace et al. (2012) stated that, for a megathrustearthquake to occur, it is necessary that the range of the smooth weak boundary surface be broad,

Appendix 2 - 20

but a geographical configuration where there are large undulations such as seamounts would
prevent such a formation.
According to Yokose et al. (2010), the Ryukyu Trench is divided into northern, central andsouthern areas along the Tokara Channel and Miyako Depression. Based upon an analysis of GPS
data, the northern, central and southern areas move laterally with respect to each other. Wu et al.
(2010) used stress inversion to find the distribution of crustal stress in the area around the Ryukyu
Trench. As a result, they reported that the stress state undergoes distinct changes along the Tokara
Channel, the reason for which is believed to be subducting of the thick crust of the Amami
submarine plateau.
2.2.4. Region-specific features of tsunami sources (far-field tsunamis)(1) From offshore Chile to offshore Peru
Large earthquakes have occurred in the region ranging from offshore Chile to offshore Peru
at intervals of several decades or more in each demarcated region. The April 2014 earthquake(MW=8.2) occurred at a location covering a seismic gap, which is called the Iquique Gap. At 7:54
on September 17, 2015 (Japan Standard Time), an earthquake, having its source off the coast ofcentral Chile, occurred (Illapel earthquake, MW=8.3), and the accompanying tsunami also reached
the coast of Japan. According to the Japan Meteorological Agency (2015), the maximum heightof the tsunami recorded was 0.8 meters at Kuji Bay, Japan.
In southern Chile, earthquakes have occurred at intervals of about 130 years. Of these, the1960 Chile earthquake tsunami was the largest earthquake ever recorded (MW=9.5). Cisternas etal. (2006) and Shishikura (2013) stated that the 1575 earthquake was the only comparable eventthat occurred prior to 1960, and reported that, over the past 2,000 years, earthquakes equivalent
to the one which occurred in 1960 have occurred on average at intervals of 300 years.
Melnick et al. (2009) divided the source regions of past earthquakes systematically at
promontory points, and reported that petrological discontinuity may act as a barrier to fractures.
Matsumoto et al. (2010) reported that, although many earthquakes have occurred along active
transform faults and sea trenches north of 46° S, there have been very few earthquakes that haveoccurred in the vicinity of 46° 30’S, suggesting a connection at the point at the triple junction ofplates off the coast of Chile where earthquakes have not occurred and ridges are subducting. In
addition, they reported that there is a gap on land in the volcanic zone along the vicinity of 46°
30’S, which is the point of the triple junction of plates off the coast of Chile.
(2) North American Cascadia subduction zone

Appendix 2 - 21

Based on the reproducibility of tsunami height, Satake and Wang (1998) estimated that theslip amount during the 1700 North American Cascadia subduction zone earthquake wasapproximately 7 meters. According to Satake et al. (1996), the entire segment of approximately
900 km ruptured during the 1700 earthquake. The current seismic gap as presented by Hatori(1998) is smaller than the 1700 rupture zone.
Scholz (2014) divided the area into four fracture patterns based on research conducted by
Goldfinger et al. (2012) on the seismicity of the Cascadia subduction zone through the Holocene,
and proposed fault models for several rupture patterns.
(3) Alaska ~ Aleutian ~ Kamchatka
The major tsunamis that have occurred from Alaska through the Aleutian to the Kamchatka
region are shown in Table 2.2.4-1.
Table 2.2.4-1 Source regions of major tsunamis (MW=8.5 or greater) occurred in North Pacific andmaximum tsunami height in Japan
Source Region

Year

Magnitude

Alaska1964

MW=9.2, Mt=9.1

0.75m: Ofunato, Iwate Pref.

1957

MW=8.6, Mt=9.0

0.48m: Kushimoto, Wakayama Pref.

1965

MW=8.7, Mt=8.6

1923 (Feb.)

MW=8.6, Mt=8.8

0.5m: Kushimoto, Wakayama Pref.

1952

MW=9.0, Mt=9.0

3.0m: Miyako and Kamaishi, Iwate Pref. etc.

Aleutian

Kamchatka

Tsunami height in Japan0.55m: Kushimoto, Wakayama Pref.
1.06m (double amplitude): Hiroo, Hokkaido* MW: Abe (1989), MacInnes et al. (2010), Tanioka (2013), Mt: Based on Abe (1989). Tsunami height: Hatori(1965), Watanabe (1998), Tsuji et al. (1998)

In addition, the 1946 Aleutian earthquake (MS=7.4 and MW=8.2) was reported to be a typicaltsunami earthquake. Also, during this tsunami, the earthquake caused submarine landslide, giving
rise to a large tsunami having a local focus along the coastline nearby.
Based on estimates of subsidence during earthquake using samples of peat and peat-silt
couplets taken on land, Shennan et al. (2007) reported that, with the exception of 1964,
megathrust earthquakes have occurred at intervals of approximately 600 years (intervals of aminimum of 180 years when estimation error is taken into account) over the past 3,800 years.
Also, they reported that the largest interval was approximately 1,000 years between 1964 and theprevious event.

Appendix 2 - 22

The largest earthquake off the coast of Kamchatka was the 1952 earthquake, and Johnson
and Satake (1999) have proposed a tsunami source model based on tsunami inversion.
Tanioka (2013) compiled the results of surveys and other investigations on tsunami deposits
and reported that tsunamis exceeding 5 meters along the coastline have occurred once every 100
to 400 years.
(4) Off the coast of Sumatra to the Andaman Sea
Rajendran (2013) reported, based upon surveys of tsunami deposits and other investigations,that megathrust earthquakes have repeatedly occurred at intervals of approximate 500 years inthe subduction zone between Sumatra and Andaman. Tanioka et al. (2006) presented a tsunami
source model (MW=9.2) for 2004 earthquake off the island of Sumatra, which was the largest ofthese. The mean fracture propagation velocity is 1.7 km/s.
Tang et al. (2013) reported, based on an analysis using the P-wave velocity structure, that
there is a thick oceanic crust in the area of the boundary along the region where the 2004 and2005 earthquakes occurred, and that it is possible this acted as a barrier to fracture propagation.
According to Koyama et al. (2012), the Indo-Australian Plate runs diagonally into the Burma
Microplate, and the Burma Microplate runs into the Sunda Microplate, which is located to theeast, in a north-northeasterly direction at a rate of approximately 37 mm/year. The Andaman
Ridge is expanding in a north-northwest direction, and the area between the Burma-Nicobar
Trench and the Andaman Ridge as well as two transform faults, the large Sumatra fault and theSagaing fault which are considered an extension of this, are heading north as the Burma
Microplate. Curray (2005) reported that the Andaman Sea is an extensible back-arc basin thatbegan to open up during the Cenozoic era resulting from an expansion that progressed in a verticaldirection to the trench due to lateral displacement of a sliver (Burma Plate) formed during the
Eocene epoch.
(5) Southeast Asia ~ Oceania
The heights of all of the tsunamis along the Japanese coast that have occurred in the past in
the sea area between Southeast Asia and Oceania have been low. The largest earthquake
magnitude in the past 100 years for the same area is either the MW=8.5 (MS=8.2), which occurredin Indonesia’s Banda Sea in 1938, or the MS=8.3 earthquake, which occurred off the southeast
coast of Mindanao island in the Philippines in 1924.
Bautista and Oike (2000) estimated, based on records of earthquakes that have remained atchurches in the Philippines, the epicenter and MS distribution of 485 earthquakes between 1608
and 1895. Of these, the largest was MS8.0. Accordingly, in the area around the Philippines, themagnitude of earthquakes over the past 400 years or so has been MW=8.5 (MS=8.3) at the largest.

Appendix 2 - 23

In other words, during a period that is almost equivalent to the period for which highly reliable
historical data is available with respect to the area around Japan, the greatest magnitude of anearthquake in the past around the Philippines has been MW =8.5.
Kawata et al. (1998) presented the results of calculations of tsunami assumed to occur in the
subduction zone of the Pacific Rim. Even in a case where a MW =9.0 earthquake is assumed in
the sea area of southeast Asia, the water level along the coast of Japan will not rise above thewater height resulting from a Chile tsunami anticipated off the coast of Chile.
According to knowledge about the seismicity of the New Guinea Trench presented by Okal
(1999), earthquakes have continuously occurred in an approximately 550-kilometer section
ranging from 134.75°E to 139.75°E. Here, the 1996 Irian Jaya (Biak) earthquake ruptured asegment extending approximately 300 km.
2.2.5. Case studies of standard fault model configuration methods, etc.
(1) Case assuming an interplate megathrust earthquake
A case study is presented for configuration of a standard fault model in a case where a MW=9class interplate earthquake is assumed in the sea area along the Nankai Trough and the area
ranging from the Kuril-Kamchatka Trench to the Japan Trench.
The methods presented by the Cabinet Office (2012) and by Sugino et al. (2014) are typicalof the methods for creating a characterized fault model for megathrust earthquakes along plateboundary. Overviews of both methods are given in Figure 2.2.5-1.
The approach to parameter configuration has been compiled into a flowchart and shown in
Figure 2.2.5-2.

Appendix 2 - 24

Total area: S
Average slip: DA

Total area: S
Average slip: DA

Background Zone

Background Zone
Large slip area

2DA

Super large slip area
3DA, 15% of S

4DA

0.333DA,
60% of S

Large slip area +Super large slip area
=20% of S(1) Cabinet Office (2012)

1.4DA,
25% of S

Large slip area +Super large slip area
=40% of S(2) Sugino et al. (2014) (for MW=8.9 or larger)

Figure 2.2.5-1 Fault modeling methods by the Cabinet Office (2012) and by Sugino et al. (2014)

Appendix 2 - 25

Figure 2.2.5-2 Parameter setting flowchart when assuming interplate megathrust earthquake* The rectangles represent the fault parameters necessary for tsunami calculation, andthe shaded items represent the items necessary before parameter setting.

(2) Case where configuration of each specific sea area is based upon fault models of past tsunami
The Japan Society of Civil Engineers (2002) presented a method for configuring standard
fault models using fault models based on past tsunami heights. An example for the sea area along
the Japan Trench and the Kuril-Kamchatka Trench (southern area) is shown below.
A flowchart for the configuration of the fault parameters is shown in Figure 2.2.5-3. Basedon fault models that best explain the run-up height records of past tsunamis which are shown in
Figure 2.2.5-4 and Table 2.2.5-1, consideration is given to maximum MW in the past as indicatedin Figure 2.2.5-5 to apply the most appropriate scaling law that reflects the earthquake initiation
pattern.
Of the sea area divisions in Figure 2.2.5-5, 3 and 8 are sea areas where tsunami earthquakes
are assumed and 4 is a sea area where an intraplate normal fault earthquake is assumed, and theothers correspond to typical interplate earthquakes.

Appendix 2 - 26

Figure 2.2.5-3 Parameter setting flowchart for standard fault model along the Japan Trench and the
Kuril-Kamchatka Trench (southern area)* Different flows between interplate and intraplate earthquakes are indicated by dashed lines.
The rectangles represent the fault parameters necessary for tsunami calculation, and theshaded items represent the items necessary before parameter setting.

Appendix 2 - 27

Figure 2.2.5-4 Position of fault models based on past tsunami heights*The figure was drawn with “SEIS-PC for Windows95” by Ishikawa and Nakamura (1997)

Table 2.2.5-1 Fault parameters of fault models based on past tsunami heights
No.

Length
L
(km)

Width
W
(km)

1-1
1-2
2
3
4
5
6
7
8

60
130
150
210
185
210
26
100
200

100
100
100
50
50
70
65
60
50

Slip
amount
D
(m)
2.2
3.5
6.0
9.7
6.6
4.0
2.0
2.3
6.5

Dip
angle
δ
(deg.)
27
20
20
20
45
15
20
10
20

Slip
angle
λ
(deg.)
115
115
80
75
270
85
85
85
95

Appendix 2 - 28

rigidityμ×1010(N/m2)
5.0
5.0
5.0
3.5
7.0
5.0
7.0
5.0
3.5

M0
×1020
(N·m)

MW

past
tsunami

6.6
22.8
45.0
35.6
42.7
29.4
2.4
6.9
22.8

7.81
8.17
8.37
8.30
8.354
8.246
7.52
7.83
8.17

1973
1952
1968
1896
1933
1793
1978
1938
1677

Segment Past Max. Mw Historical tsunami
1952
1
8.2
1968
2
8.4
1896
3
8.3
1611
4
8.6
1793
5
8.2
1978
6
7.7
1938
7
7.9
1677
8
8.2

Figure 2.2.5-5 Sea area segmentation and past maximum MW

Appendix 2 - 29

Table 2.2.5-2 Example of parameter setting procedure for standard fault model near the Japan Trench
and the Kuril-Kamchatka Trench (southern area)
Typical interplate thrustearthquake
Scaling law

Fault length

Intraplate normal fault

Tsunami earthquake

earthquake

Width should have an upper limit
A suitable scaling law is applied to the fault models based on past tsunami heights which is
set in the vicinity of expected positions
A suitable scaling law is applied to the fault models based on past tsunami heights which is
set in the vicinity of expected positions

Fault width

Width should have an upper
limit when the depth exceeds

Upper limit of the width is 50km

50 km
Slip Amount
Depth of upperedge of the fault
plane
Strike angle

Dip angle

Slip angle

A suitable scaling law is applied to the fault models based on past tsunami heights which is
set in the vicinity of expected positions
Depth is to be determined on the basis of the depth of
the upper surface of the subducting plate

Depth is set to zero

Strike direction is set according to the strike direction of the upper surface of the subducting
plateSame as the fault models based on past tsunami heights
Slip angle is decided on the basis of the strike and slip

Same as the fault models

direction

based on past tsunami heights

3.5 × 1010 (N/m2) when depth is less than 20 km
Shear modulus

7.0 × 1010 (N/m2) when depth is more than 20 km
5.0 × 1010 (N/m2) when the fault model extends over both regions

2.3. Earthquakes anticipated along the eastern margin of the Japan Sea(1) Knowledge about past tsunamis, etc. on the eastern margin of the Japan Sea
On the eastern margin of the Japan Sea, a distinct plate boundary has not formed, but M=7.5
class earthquakes have occurred in a region of narrow width, which is the eastern margin of theJapan Sea. The upper limit of the size of earthquakes that have occurred in the surrounding area
is M7.2. Moreover, multiple references have indicated a seismic gap for large earthquakes off thecoast of Akita.

Appendix 2 - 30

On the basis of the characteristics and strike of active faults, Okamura (1998) has broadlyclassified the eastern margin of the Japan Sea into a northeastern area (depth of 2,000m or lessnorth of the Shakotan Peninsula), central area (eastern margin of the Japan Basin from west of
the Tsugaru Peninsula to northwest of the Shakotan Peninsula), and southern area (eastern marginof the Yamato Basin from the area around Sado Island to northwest of the Oga Peninsula).
Flank collapse is regarded as the most likely cause of the 1741 Oshima-Ōshima Island
tsunami. Satake and Kato (2000) as well as Satake (2000) used numerical elevation data for landand submarine topography to re-create the original sector from the collapsed topography to thenorth of Oshima-Ōshima Island, and conducted numerical simulations of tsunami based on thisreproduction.
There is an approach that holds that the active fault distribution and aftershock distribution(corresponding for the most part to the tsunami source region) do not coincide based upon acomparison of aftershock distribution and the results of investigations of active faults conducted
subsequent to the 1993 earthquake off the southwest coast of Hokkaido (Okamura, 1993). On theother hand, the Ministry of Land, Infrastructure, Transport and Tourism et al. (2014) configured
probable maximum tsunamis based upon active fault distribution.
The Japan Coast Guard’s Hydrographic Department (2001) reported that the Shirabeshi
Seamount and other submarine volcanic edifices are distributed in the gap between the 1940
earthquake off the coast of Shakotan and the 1993 earthquake off the coast of Southwest
Hokkaido, and, between the source region of the 1983 earthquake in the central part of the Japan
Sea and the 1993 earthquake off the southwest coast of Hokkaido, there is the Matsumae Plateau,
which is a horst that formed when volcanic edifices and the Japan Sea expanded, including
Oshima-Ōshima and Oshima-Koshima, separating the source regions of both. Also, Kyuroku
Island is located on the southern edge of the source region of the 1983 earthquake in the central
part of the Japan Sea, and, in the sea area ranging from the 1940 earthquake off the coast of
Shakotan to the 1983 Nihonkai Chubu earthquake, the source region is divided by the seafloor
where it is predicted that the crustal structure is different from the volcanic edifices, horst andother surrounding areas.
(2) Magnitude of earthquakes on the eastern margin of the Japan Sea as considered based on crustal
structures
1) Data used
Here, the models of inland earthquakes from around the world have been collected andanalyzed in order to clarify the relationship between crustal structure and earthquake magnitudewith respect to inland-type earthquakes that occur within the Earth’s crust.

Appendix 2 - 31

The collected data is given below. In particular data was extracted from documentary
records when models were collected from a common standpoint with respect to large inland
earthquakes.
•Earthquake magnitude and fault models:• The fault specifications that Murotani et al. (2015) used for reviewing the scaling laws
pertaining to inland mega-fault systems• The highly reliable data, which was extracted by Hashimoto (2007) from the objects
analyzed by Stirling et al. (2002) concerning scaling laws, that includes data on
subsurface fault length (adopted also in Murotani et al., 2015)• Fault model that can explain run-up height of past tsunami on the eastern margin of theJapan Sea as adopted by the Japan Society of Civil Engineers (2002) (since 1900)(Figure 2.3-1)• Data added for this review to the aforementioned models:• Specifications of large earthquakes that Hanks and Bakun (2002) added when
considering scaling laws for inland earthquakes, but parameters have been revised for
those where width has been assumed when estimating earthquake magnitude.
• Foremost large inland earthquakes that have occurred in recent years• 2001 China Kunlun (Kokoxili) earthquake• 2001 India Bhuj (Gujarat) earthquake•Data on crust thickness• Crust 1.0, a global model at 1x1 degrees of the crust structure which was developed by
Laske et al. (2013) has been used.
•Epicenter locations• Epicenter locations are mainly based upon USGS Earthquake Search. Values found in
documentary records have been used for those locations for which there is no data in
the USGS Earthquake Search.

Appendix 2 - 32

Historicaltsunami
1940
ShakotanOki

S
MW

7.70

6.93
1964
Niigata
7.51
1983
Nihonkai-Chubu1993
Hokkaido
NanseiOki

7.74

7.84

L
2

(km )

(km)

W
(km)

D
(m)

d
(km)

θ
(deg.)

δ(deg.)λμM0(deg.)(×1010N/m2)(×1020
Nm)

4050

135

30

3.2

0

347

40

90

3.5

4.54

900

45

20

3.3

1

202

60

90

3.5

1.04

300

20

15

3.0

1

189

60

90

3.5

0.32

813

32.5

25

5.3

0

200

60

52

3.5

1.51

813

32.5

25

2.9

0

200

60

90

3.5

0.82

1200

40

30

7.6

0

22

40

90

3.5

3.19

1800

60

30

3.05

0

355

25

80

3.5

1.92

2250
650

90
26

25
25

5.71
4.00

10
5

188
175

35
60

80
105

3.5
3.5

4.50
0.91

458

30.5

15

12

5

150

60

105

3.5

1.92

Ref.
Japan
Society of
Civil
Engineers(2002)
Nogueraand Ku.
Abe (1992)
Kato andAndo(1995)Aida (1984)
Model-10
Takahashi
et al. (1995)
DCRC-26
model

Figure 2.3-1 Fault models based on the past tsunami heights on the eastern margin of the Japan Sea(the Japan Society of Civil Engineers, 2002)

2) Relationship between crust thickness and MW as well as fault length
When the relationship between crust thickness and MW as well as fault length for the
consolidated intraplate earthquakes from around the world is plotted, the arrangement is createdAppendix 2 - 33

as shown in Figure 2.3-2 and Figure 2.3-3.
• In areas where crust thickness is less than approximately 40 km, no earthquake
exceeding MW= 8 has occurred.
• The upper limit of fault thickness appears to be conditioned upon crust thickness.
Generally, 7.5 times the crust thickness is the upper limit.
9
8.5

Murotani et al.(2015)8
7.5

Stirling et al.(2002)

Mw

7
Crustal Eq. in the world
added in this study

6.5
6

Eastern margin of Japan
Sea (JSCE, 2002)

5.5
5Eastern margin of Japan
Sea (This study)

4.5
4
0

10

20

30

40

50

60

70

80

thickness of crust[km]Figure 2.3-2 Relationship between crustal thickness and MW at the epicenter position of the crustal
earthquake in the world*Crustal thickness is the sum of the upper, middle and lower crust
500
1906 San Francisco

450
Murotani et al.(2015)
400
1958 Alaska

Stirling et al.(2002)

fault length [km]350
2002Alaska

300

Crustal Eq. in the world
added in this study

250

Eastern margin of Japan
Sea (JSCE, 2002)

200

Eastern margin of Japan
Sea (This study)

150
100
50
0
0

20

40

60

80

thickness of crust[km]Figure 2.3-3 Relationship between crustal thickness and fault length at the epicenter of earthquake inthe world crust*Crustal thickness is the sum of the upper, middle and lower crust3) Crustal structure of the eastern margin of the Japan Sea
Kodaira (2013) and No et al. (2014) reported that the 1983 Nihonkai Chubu earthquake

Appendix 2 - 34

occurred in the boundary between island arc crust and transition crust, and this fault reached as
far as the vicinity of the Mohorovicic discontinuity. The earthquake source fault reaches a depthof up to 20 km. This event differs from an upper intra-crustal fault resulting from an ordinary
active inland fault, and its characteristics are believed to appear in areas where plates collide on
the eastern margin of the Japan Sea.
According to Ichijo et al. (2010), Hasegawa (2002), Shiba and Uetake (2011), Nakahigashi
et al. (2012) and Nakahigashi et al. (2013), the same tendency has been observed even in areas
where large earthquakes occurred in the past on the eastern margin of the Japan Sea besides the1983 Nihonkai Chubu earthquake.
2.4. Earthquakes anticipated at submarine active faults
2.4.1. Basis for standard fault model configuration and other specifics(1) Knowledge about past tsunamis, etc. in sea area around Southwest Japan
In the area around Southwest Japan, no large tsunami has occurred with the exception of
two, the 1792 tsunami resulting from the Mt. Mayuyama collapse and the 1596 tsunami in Beppu
Bay. Of these, Abe (1999) reported that, although the scale of the 1596 tsunami in Beppu Bay
was abnormally large compared to the size of the earthquake, its cause has not been able to be
identified.
On the Japan Sea side, there have been cases where small tsunamis have occurred due toM7 class earthquakes that struck in locations close to the coastline.
There is a legend about a megathrust earthquake tsunami that occurred in 1026 (3rd year of
the Manju era) off the coast of what is currently Masuda City in Shimane Prefecture that caused
damage to the coastal area. Based upon excavation and research conducted along the Masuda
River, a position has been stated that, although tsunami deposits and unique sand layers havebeen discovered which indicate carbon isotopes dating to approximately 1,000 years ago, there
are no entries about tsunami in major historical records of the time (Minoura et al., 1993). In the
future, as the collection of data advances with regard to whether or not there were any tsunamis
and, if there were, what were the causes, tsunami height distributions, etc., there is the possibility
that such tsunami may serve as material for review in order to configure standard fault models.
(2) Scaling laws for mega-fault systems
Of the data on inland crustal earthquakes that Takemura (1998) followed that served as thebasis for scaling laws applied to submarine active faults and the eastern margin of the Japan Sea
by Japan Society of Civil Engineers (2002), the longest fault length was 85 km associated with

Appendix 2 - 35

the 1891 Nobi earthquake, and even longer fault lengths are extrapolated areas. Here, case studies
are presented of reviews conducted in recent years of scaling laws for mega-fault systems.
1) Murotani et al. (2015)• Reference data:Of the earthquakes in mega-fault systems exceeding a length of 80 km that have occurredinland around the world and medium-sized earthquakes that have occurred in recent
years, 11 were selected for analysis conducted using seismic tsunami shapes andsurveys conducted of surface earthquake faults. In cases where there are multiple
analysis results, the mean was selected.
Furthermore, of reliable data selected by Hashimoto (2007) from a database provided by
Stirling et al. (2002), 40 earthquakes were added for which the subsurface fault lengths
were obtained.
• Results :The ratio of the earthquake source fault length and the surface fault length is almost 1:1.
The maximum displacement observed on the Earth’s surface (Dsurf) is generally 2 ~ 3times the mean slip amount at the earthquake source fault.
Dsurf and the maximum slip amount at the earthquake source fault is a proportional
relationship of almost 1:1.
Dsurf saturates 10 m when the length of the earthquake source fault is roughly 100 km.
When width W=18 km, then S=1.0×1017 M0, and a scaling relationship has been
proposed where slip amount saturates here.
2) Shaw and Scholz (2001)
Shaw and Scholz (2001) analyzed the parameters of intraplate and interplate earthquakes
around the world, and reported that, when the ratio of L/W exceeds ten-fold, then slip amountreaches an upper limit. However, W is fixed at 15 km and corresponds to the thickness of theseismogenic layer. Moreover, the following relational expression has been derived.
D    (L 2)(L

D    1/1/ L  1 / 2W (L > 2W)

2W)

3) Manighetti et al. (2007)
Manighetti et al. (2007) proposed a scaling law for slip amount in relation to earthquakesthat occur in multiple segments. The smaller the number of segments, the quicker slip amountsaturates over total length. Also, the greater the number of segments, the smaller the saturated
slip amount. The number of interlocking segments depends on the strength of the barrier between

Appendix 2 - 36

segments, and this strength is reported to vary depending upon the maturity of the fault.
4) The Headquarters for Earthquake Research Promotion’s treatment of mega-fault systems in“Methods for Long-Term Assessment of Active Faults”
Taking into account research conducted by Manighetti et al. (2007), the “Methods for LongTerm Assessment of Active Faults” (Headquarters for Earthquake Research Promotion, 2010)
states: “With respect to active mega-fault systems where the length exceeds 100 km, thepossibility that the amount of displacement during activity may be saturated has been
indicated…., so, in cases where length is not greater than four times the width of the fault plane,
earthquake magnitude is estimated based upon the L-M formula provided by Matsuda (1975),
and, in cases exceeding this length, a model has been configured where multiple demarcatedsegments rupture so that the length does not exceed four times”. In other words, in cases wherelength exceeds four times the width of the fault plane, a model has been provided that arranges
models, which apply the scaling relationship for each demarcated sector into many parts, in aseries.
2.4.2. Case studies of standard fault model configuration methods, etc.
The Ministry of Land, Infrastructure, Transport and Tourism et al. (2014) also created models forsubmarine active faults other than in the eastern margin of the Japan Sea. Models have been configured
for 60 faults (including submarine active faults in the eastern margin of the Japan Sea) throughout theentire Japan Sea.
2.4.3. Tsunami source configuration methods for probable maximum tsunami(1) Configuration method for slip angle based on relationship between regional stress field and fault
plane angle
1) Examination policy
With regard to cases where data has been obtained about the location, strike and length ofsubmarine active fault, methods are to be examined for estimating the static fault parameters
necessary for numerical simulations of tsunami.
The oceanic crust far away from the coastline is relatively stable, and no large earthquakes
have occurred in this area in the past. On the other hand, in sea areas relatively close to thecoastline, seismic activity has been reported in the past that includes large earthquakes, and there
is also the possibility of such activity in the future. This examination will focus on the upper

Appendix 2 - 37

intraplate earthquakes that occur at submarine active fault relatively close to the coastline. On thesea bottom in coastal waters, crustal structures have structures similar to those on land andhypocenter distribution and stress fields are also believed to be connected with those in land areas,so utilizing knowledge and data about inland crustal earthquakes, consideration will be given tothat which makes it possible to configure tsunami source models for probable maximum tsunamis.
2) Occurrence patterns of inland crustal earthquakes
Along with the size of an earthquake, the width of the fault plane increases, but it has been
pointed out that an upper limit is reached at a certain width depending on location. Fracture zones
for shallow earthquakes are limited to seismogenic layers, and the scaling law for fault
parameters changes before and after the upper limit for the fault width.
When the fracture of one rectangular fault extends across all layers of seismogenic layer
thickness He, fault width W takes a value commensurate with dip angle δ and is expressed using
the following equation.

W 

He……………………………………………(2.4.3.1)
sin 

According to Ito et al. (1995) and the Fukuoka Regional Headquarters of the Japan
Meteorological Agency (1998), the maximum depth of inland crustal earthquakes is believed tobe between 15 and 20 km.
Using the earthquake mechanism analyses detailed in the Japan Meteorological Agency’s
Seismological Bulletin of Japan, the fracture surfaces were identified for 31 examples ofearthquakes having a hypocenter depth of less than 20 km and a magnitude of 5.0 or greater asreported by the Japan Meteorological Agency and occurred inland in southwestern Japanbetween 1973 and August 1998. The frequency distribution of dip angle is given in Figure 2.4.31, and these earthquakes occurred generally at high angles (45 ~ 90°).

Appendix 2 - 38

Figure 2.4.3-1 Frequency distribution of dip ales of shallow inland earthquakes occurred in Southwest
Japan

According to the analysis of the earthquake mechanisms provided by Global CMT, theorientation of the P and T axes is uniform for each region and does not depend upon earthquake
type. In other words, with regard to earthquakes of MW=5.0 or greater, fault motion corresponds
well with wide-area stress field.
(2) Configuration methods for slip angle based on the relationship between regional stress field andfall plane angle
The dip angle and other characteristics of faults may be configured based upon surveys. In
cases where data is not well-defined, the following may serve as a guide, which is based upon avariety of knowledge.
• Depth of fault upper edge: 0 ~ 5km• Dip angle: 45 ~ 90° (for southwestern Japan) and 30 ~ 60° (Chuetsu region)• Slip angle: Range found based upon regional stress field and dip angle
Of these, the range found based upon regional stress field and dip angle may be configured
based upon the principle shown in Figure 2.4.3-2.

Appendix 2 - 39δ: dip angle
θ : strike angle
λ : slip angle

Figure 2.4.3-2 Schematic diagram of the relationship between focal mechanism and fault motion* Based on the principle of the focal mechanism, the slip angle can be geometricallyestimated from the stress field around the active fault and the strike and dip angles of thefault.The principal pressure (P) axis and the principal tension (T) axis intersect with thetwo node faces at 45°, and the slip vector coincides with the normal vector of the auxiliary
plane (the node which is not the actual fault plane) (JSCE, 2002).
The orientation of the P axis is believed to be within a range of 90° ~ 120° for southwesternJapan and 110° ~ 140° for the Chuetsu Region (both are clockwise from the north).
Although there are descriptions pertaining to the azimuth angle of the P axis, trends havealso been seen regarding dip (dip angle) of the P axis. An analysis of earthquakes less than M=5.0
and a depth of 30 km that have occurred in Southwest Japan and are based on analyses of suchmechanisms by various institutions is given in Figure 2.4.3-3. It is found that the plunge of the P
and T axes is within 32° and their principal axes are almost horizontal.

Harvard MT （Jan.1976～Dec.2009)

F-net MT （Jan.1997～Dec.2009）45

Plunge of P or T axis (deg.)

Plunge of P or T axis (deg.)

45
40
35
30
25
20
15
10
5
0
0

10

20

30

40

50

60

70

80

Plunge of P‐axis(compressional)

40
35
30
25
20
15

Plunge of T‐axis(extensional)

10
5
0

90

0

10

20

Fault Dip (deg.)

40

50

60

70

80

90

Fault Dip (deg.)

JMA CMT（Sep.1994～Dec.2008）

JMA Focal Mechanism from Initial-Motion （Jan.1973～Dec.2008）
45

Plunge of P or T axis (deg.)

45

Plunge of P or T axis (deg.)

30

40
35
30
25
20
15
10
5
0

Pure dip‐slip
fault

40
35
30
25
20
15

Pure strike‐slip
fault

10
5
0

0

10

20

30

40

50

60

Fault Dip (deg.)

70

80

90

0

10

20

30

40

50

60

70

80

90

Fault Dip (deg.)

Figure 2.4.3-3 Distribution of P and T axes of upper crustal earthquake occurred in Southwest Japan

Appendix 2 - 40

(3) Basic fault parameter configuration methods for probable maximum tsunami
1) Procedure based on relationship between fault length and moment magnitude
A flowchart for the fault parameter configuration method for a tsunami anticipated at
submarine active fault (Koba et al., 2001) is shown in Figure 2.4.3-4.

Figure 2.4.3-4 Tsunami standard fault model setting flowchart assumed for submarine active fault(Procedure based on relationship between fault length and moment magnitude)*The rectangles express the fault parameters necessary for tsunami calculation, and the grayed items
express information needed prior to setting the parameters. In cases where the moment magnitude
is set prior to the fault length, the fault length is computed from the moment magnitude along theflow indicated by the broken line.
Cases where dip angle and other parameters are well-defined based on surveys of active faults orother data may be treated as definitive.

The methods for configuring the parameters have been compiled in Table 2.4.3-1. The depthof the upper edge of faults assuming a shallow earthquake is given as 0 km. Also, from theaforementioned range of 15 ~ 20 km, the thickness of the seismogenic layer has been limited to
15 km, a depth where slip amount increases.
Based on the principles of earthquake mechanisms, slip angle may be estimatedgeometrically from the strike and dip angles and the stress field in the area around the fault. A
conceptual diagram is shown in Figure 2.4.3-5. The principle axis of pressure (P axis) and theprinciple axis of tension (T axis) incline 45° from the two nodal planes a and b, and the slip vector

Appendix 2 - 41

coincides with the direction of the normal line of the auxiliary plain (nodal plane b, which is not
an actual fault plane). The orientation of the stress access may be estimated by referencing
analyses of earthquake mechanisms of past earthquakes as well as previous case studies showing
regional stress field in regions of Japan (see for example Tsukahara, 1999).
Similar to what was done regarding the eastern margin of the Japan Sea, those relationshipequations provided by Takemura (1998) that are given below and express the relationshipbetween fault length and earthquake magnitude are applied for the scaling law.
i) When fault width has reached the upper limit

log L ( km)  0.75 M w  3.77, L  D, W  const . ……………(2.4.3.2)ii) When fault width has not reached the upper limitW

2
L, L  W  D …………………………………………(2.4.3.3)
3where, L represents fault length and D slip amount. Also, MW is moment magnitude and isconnected to fault parameters using the following relationship.

log M 0 ( N  m)  1.5M w  9.1 …………………………………(2.4.3.4)
D

M 0 ……………………………………………………(2.4.3.5)
LW

where, μ represents rigidity.
In cases where fault length and seismogenic layer thickness are given, then・when fault width has reached the upper limit: equations (2.4.3.1), (2.4.3.2), (2.4.3.4), and(2.4.3.5)
・when fault width is below the upper limit: equations (2.4.3.3), (2.4.3.4), and (2.4.3.5) areapplied, and, if the relationship of both fields is connected continuously, then fault widthand slip amount may be computed.

Appendix 2 - 42

Table 2.4.3-1 Method of setting basic fault parameters of tsunami assumed for submarine active fault(Procedure based on the relationship between fault length and moment magnitude)
Parameter

Setting procedure

LengthFault length is to be set on the basis of the results of an active faults survey.

(L)
Width
(W)
Dislocation(D)

When determining the length from MW, it follows the scaling law.
Width is set on the basis of the thickness of seismogenic layer and dip angle.
D = M0 / μLW
Where, logM0 (Nm) = 1.5 MW + 9.1 .

Depth of upper edgeof the fault plane

0 km

(d)
Strike angle(θ)
Dip angle(δ)
Slip angle(λ)
Shear modulus(μ)

On the basis of the result of active faults survey
On the basis of the earthquake focal mechanism solutions, or set from 45° to90°
Determined by strike direction, dip angle and direction of principle stress axis.

3.5 × 1010(N/m2)
1) W < “thickness of the seismogenic layer” / sinδW = 2L / 3
L ∝ W ∝ D

Scaling law2) W > “thickness of the seismogenic layer” / sinδW = “thickness of the seismogenic layer” / sinδlogL (km) = 0.75 MW - 3.77 (Takemura’s formula)
L ∝ DAppendix 2 - 43

Figure 2.4.3-5 Schematic diagram of the relationship between focal mechanism and fault motion(Drawing based on Sato (1989))

2) Procedure based on relationship between fault area and moment magnitude
The procedure based upon the relationship between fault area and moment magnitude isapplied to fault models assuming slip heterogeneity. For more specific details, refer to casestudies of such applications presented in appendix volume 6.
Differences from the procedure based on the relationship between fault length and moment
magnitude are given below.
First, in cases where fault length and seismogenic layer thickness are given, the equation forwhen the fault width reaches the upper limit (2.4.3.1) is applied and the equation for when thefault width is below the upper limit (2.4.3.3) is applied to compute fault area S.

S  L W
Next, the following scaling laws are used to compute M0 based upon fault area S.
3

M 0  ( S / 2.23  10 9 ) 2  10  7( M w  6.5)

M 0  ( S / 4.24  10 5 ) 2  10 7(6.5  M w  7.7)
(Irikura and Miyake, 2001)

M 0  1.575  S  10

11

(7.7  M w )(Prepared based upon Ministry of Land, Infrastructure, Transport and Tourism et al. (2014))
A flowchart of the fault parameter configuration method based upon the relationshipbetween fault area and MW is shown in Figure 2.4.3-6.

Appendix 2 - 44

Figure 2.4.3-6 Tsunami standard fault model setting flowchart assumed for submarine active fault(Procedure based on relationship between fault area and moment magnitude)*The rectangles express the fault parameters necessary for tsunami calculation, and thegrayed items express information needed prior to setting the parameters. In cases where

MW is set prior to the fault length, the fault length is computed from MW along the flow
indicated by the broken line. Cases where dip angle and other parameters are well-defined
based on surveys of active faults or other data may be treated as definitive. Matters related
to slip heterogeneity and kinematic fault parameters have been omitted.

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Appendix 2 - 56

Chapter 3. Examination of Effects of Tsunami Source Uncertainty on Tsunami Height
3.1. Typical factors in parametric studies of uncertainty concerning tsunami resulting from fault
motionAlthough, in principle, parametric studies use a standard fault model to examine the factors(indicated with a circle) shown in Table 3.1-1, factors determined to have low uncertainty may be
excluded.
Table 3.1-1 shows the approach employed for limited sea areas. When assessing probablemaximum tsunamis in other sea areas, factors may be selected for implementing parametric studies
based on similar examination methods.

Appendix 3 - 1

Table 3.1-1 Parameters to be examined in parametric studies (X: Factors to implement parametric studies in principle)
Static parameters
Region or type of earthquake

Plane
Position

Position oflarge slip

Strike angle

Dip angle

regionKinematic parameters
Dip

Slip angle

Depth ofdirection(Rake)

fault top

Rupturestarting
point

Rupturevelocity

Rise time

In case of heterogeneous model:Interlocking of interplate thrust fault
earthquake and tsunami earthquake,

X*1

X

-

-

-

X*2

-

X

X

X

X*1

-

X

X

-

X

X

-

-

-

X

-

X

X

-

X

-

-

-

X

-

X

X

-

X

-

-

-

X

X

X

X

X*4

X

-

-

-

-

X*5

-

X*5

X*6

X

-

-

-

or interplate thrust fault earthquake
In case of homogeneous model:Interplate thrust fault earthquake

Appendix 3 - 2

Along the Japan Trench (Intraplate
normal fault)(Fixed at 270°)

In case of homogeneous model:
Along the Japan Trench (Tsunami

X*2earthquake)
The Eastern margin of the Japan Sea(Crustal earthquake)
Submarine active fault(Upper-crust earthquake)(Fixed at 90°)

X*3

*1 Except when applying the standard fault model to the entire seismic region*2 Set according to strike angle considering uncertainty in sliding direction*3 Set according to dip angle considering the variancevariance of stress field*4 Westward inclination and eastward inclination*5 Fixed when obvious by survey*6 Set both directions for faults without information

3.2. Range of factors for which uncertainty is relatively high in parametric studies
For the eastern margin of the Japan Sea, the standard fault model configures the dip angle between
30° and 60°, and in cases where the presence of submarine active faults is unknown, the dip is believed
to be between 45° and 90° (Southwestern Japan) or between 30° and 60° (Chuetsu region). The
orientation of the P axis (principle axis of pressure) in a regional stress field is believed to be held
within a range between 90° and 120° for southwestern Japan and between 110° and 140° for the
Chuetsu Region (both are clockwise from the north). In these cases, the parameters of the standard
fault model have a range.
3.3. Case studies examining the impact that uncertainty about tsunami source has on tsunami height
Here, the impact that uncertainty involving the fault parameters of a tsunami source model has
on tsunami height along the coastline is assessed by performing numerical simulations of tsunami. Of
the static parameters examined such as strike and dip angle, the impact due to parameters related to
uncertainty associated with dynamic fracture of faults such as the fracture initiation point were
examined for the Nankai Trough and the eastern margin of the Japan Sea.
3.3.1. Impact of moment magnitude
Because the magnitude of the tsunami height is mainly controlled by the magnitude of slip
amount of the fault plane, the effect of moment magnitude (MW) varies depending upon the scaling
law applied. The relationship between MW and Slippage D for three scaling laws is given below.
(1) Case where an upper limit is not set for the fault plane: log D ∝ 0.5 MW(2) Case where an upper limit is set only for the width of the fault plane: log D ∝ 0.75 MW(3) Case where an upper limit is set for the length and width of the fault plane: log D ∝ 1.5 MW
When this relationship is utilized, if MW is increased 0.1, slip amount will increase by 1.12 times
in the case of (1), 1.19 times in the case of (2), and 1.41 times in the case of (3).
Cases where numerical simulations have actually been performed are shown in Figures 3.3.1-1
through 3.3.1-3. Each figure shows the lines of magnification (inclination) anticipated based upon theincrease in slip amount. As is clear from the diagrams, the rate of increase in the tsunami height basedon the numerical simulations correspond for the most part to the rate of increase of slip amount.

Appendix 3 - 3

0 .6

0.6

00.2
.2
lo g1 0 ( 津波水位)

log (tsunami height)

00.4
.4

Calculated maximum
計算
water level ascent
最高水位

0.0

0 .0

-0.2

-0 .2

-0.4

-0 .4

-0.6

-0 .6

-0.8

1.12 倍の傾き
倍の線
1.12

-0 .8

-1.0

-1 .0

77..22 77..44 77..66 77..88 8 8. 0TOKAI
88 ..22 88 .4. 4 88 .6. 6 88 .8. 8 9 9. 0 99 .2. 2
Mw

MW

Figure 3.3.1-1 Example of examination of the influence of MW on tsunami water level (Scaling law(1), Along Japan Trench)log log10(津波水位)(tsunami height)

0.4
0.4
0.2
0.2

Calculated maximum
計算
water level ascent
最高水位

0.0
0.0

-0.2
-0.2
-0.4
-0.4
1.19
1.19倍の傾き
倍の線

-0.6
-0.6
-0.8
-0.8
7.2
7.2

7.4
7.4

7.6
7.6

7.87.88.08.08.2 8.2

M

Mw W

Figure 3.3.1-2 Example of examination of the influence of MW on tsunami water level (Scaling law(2), Sea area around Southwest Japan)log（津波水位）log(tsunami height)log10(津波波高
)

1.2
1.2

1.41 倍の線

1.41 倍の傾き

1.0
1.0
0.8
0.8
0.6
0.6

計算最高水位

0.4
0.4
0.2
0.2

Calculated maximum
water level ascent

0.0
0.0

7.8

7.9
7.9

8.08

8.18.1

8.28.2

8.3 8.3

Mw

MW
Figure 3.3.1-3 Example of examination of the influence of MW on tsunami water level (Scaling law(3), Nankai Trough)Appendix 3 - 4

3.3.2. Impact of plane position of tsunami source(1) Example of sea area along the Japan Trench
Figure 3.3.2-1 shows the distribution of the maximum water level ascent along the coastline
and the plane position of the examined tsunami source. The horizontal axis is normalized using
the maximum value for all cases and is a relative ratio. For the fault models, MW=7.6, Fault length
L=77 km, Fault width W= 46.3 km, and Slippage D= 1.81 m are the same, three cases wereconfigured for the offshore direction so that they would be aligned with a plate boundary surface
having a dip angle of 10° (fault depths for the three cases: fault upper edge depth d=15 km, 27
km and 39 km) and three cases for the north-south direction so that there were a total of 3x3 cases.
Dip angle δ= 10° and the slip angle λ=85° were uniform.
The basic grid size along the coastline is 320 m. However, somewhat more detailed grids
have been used at points where the grid size is 160 m at solid triangles and 80 m at solid star. In
the distribution of the maximum water level ascent along the coastline, features are seen such as
the tendency for the maximum water level ascent to become greater as the tsunami source ispositioned in front of a target point as well as the tendency for the maximum water level ascent
to become greater as the tsunami source is positioned in sea areas where the water depth is greater
offshore.
Relative ratio of maximum water level ascentFigure 3.3.2-1 Influence of tsunami source location around the Japan Trench on coastal maximum
water level ascent distribution(2) Example of sea area along the eastern margin of the Japan Sea
Figure 3.3.2-2 shows the distribution of relative ratios of the maximum water level ascent

Appendix 3 - 5

along the coastline and the plane position for the examined tsunami sources. The fault models
were configured so that MW=7.8, L=120 km, W=17.3 km, Slippage D=8.66 m, as well as δ=60°
and λ=90° in a western inclination are uniform, and only the position is changed for the five cases.
The basic grid size along the coastline is 800 m. A 400 m grid size has been used at points
where consideration is given to the effect that the Yamato Ridge, Oki Islands and other features
have on the tsunami propagation characteristics. In the distribution of the maximum water levelascent along the coastline, features are seen such as the tendency for the maximum water levelascent to increase as the tsunami source is positioned in front of a target point as well as a greater
impact due to the propagation route than the position of the tsunami source in cases where theDistance along the coastline (km)Relative ratio of max. water level ascent

Relative ratio of max. water level ascenttarget point is far from the tsunami source.

Distance along the coastline (km)

Fault position
Grid size (m)Figure 3.3.2-2 Influence of tsunami source location in the eastern margin of the Japan Sea on coastal
maximum water level ascent distribution
3.3.3. Impact of fault upper edge depth
Examples of cases examined where only the depth of the fault upper edge was changed without
altering other conditions are shown in Figure 3.3.3-1 (earthquakes in sea areas along the eastern marginof the Japan Sea) and Figure 3.3.3-2 (earthquakes in sea areas along the Japan Trench).

Appendix 3 - 6

For the examination of earthquakes along the eastern margin of the Japan Sea as shown in Figure
3.3.3-1, fault models were configured for four cases where MW=7.8, L=120 km, W=17.3 km, Slippage
D=8.66 m, λ=90° and Plane position were uniform, and the dip direction and angle were changed. The
vertical axes in the figure indicate the ratio of the maximum values in all cases, and the effect that
depth of the fault upper edge has on maximum water level ascent varies depending upon the target

Matsumae

Relative ratio of max. water level ascent

Shakotan-Misaki

最大水位上昇量の相対比

最大水位上昇量の相対比

Relative ratio of max. water level ascentpoint, and no clear trends have been able to be discerned.

Relative ratio of max. water level ascent

Depth of fault top (km)Depth of fault top (km)FukauraShakotan-Misaki

Relative ratio of max. water level ascent

Depth of fault top (km)Matsumae

SakataFukauraFault position: Westward inclination at 30 deg.
: Westward inclination at 60 deg.
Sakata: Eastward inclination at 30 deg.
: Eestward inclination at 60 deg.

Depth of fault top (km)Figure 3.3.3-1 Example of examination of the influence of upper edge depth of fault on maximum
water level ascent in the eastern margin of the Japan Sea
For the examination of earthquakes in the sea area along the Japan Trench as shown in Figure
3.3.3-2, Fault (1) (normal fault earthquake) and Fault (2) (tsunami earthquake) were taken into
consideration. The fault models for the normal fault earthquake set MW=8.5, L=219 km, W=59.2 km,
Slippage D=7.81 m, δ=45°, λ=270°, and Plane position as uniform, and the fault models for tsunami

Appendix 3 - 7

earthquake set MW=8.2, L=200 km, W=50.0 km, Slippage D=7.18 m, δ=20°, λ=95°, and Plane positionas uniform. The effect of the depth of the fault upper edge was not straightforward, and there wereboth points where the maximum water level ascent increased as the fault upper edge depth deepened
as well as points where the reverse was observed.

(a)

Soma
HironoHitachi(b)

HironoDepth of fault top (km)Depth of fault top (km)Hitachi

Katsuura

Relative ratio of max. water level ascent

Relative ratio of max. water level ascent

Relative ratio of max. water level ascent

Soma

Relative ratio of max. water level ascentKatsuura

Depth of fault top (km)Depth of fault top (km)：(a ),：(b)

Figure 3.3.3-2 An example of examination of the effect of the upper edge depth of fault on the
maximum water level ascent in the sea area along the Japan Trench
3.3.4. Effect of strike
Cases examined where only strike was changed without changing other conditions are shown inAppendix 3 - 8

Figure 3.3.4-1 (earthquakes in sea areas along the eastern margin of the Japan Sea) and Figure 3.3.42 (earthquakes in sea areas along the Japan Trench).
Figure 3.3.4-1 shows the plane position, distribution of maximum water level ascent along thecoastline, and the effect of strike at each point for the examined tsunami sources. The fault models
were configured so that, for five cases, MW=7.8, L=120 km, W=17.3 km, Slippage D=8.66 m, as well
as a western inclining δ=60° and λ=90° and d=1 km are uniform, and only strike is varied. By varying
strike, points are also seen where the magnitude of the reference strike varies between 0.6 and 1.8
times. Also, there is a tendency for the maximum water rise to be greater at strike where the fault is
upright with respect to the target point.

Appendix 3 - 9

Relative ratio of max. water level ascentDistance along the coastline (km)ShakotanMisaki
Matsumae
FukauraSakataFault position

Relative ratio of max. water level ascent

SakataGrid size(m)Shakotan-Misaki

Strike Angle (deg.)

Strike Angle (deg.)

FukauraMatsumae

Relative ratio of max. water level ascent

Relative ratio of max. water level ascent

Relative ratio of max. water level ascent

Reference Strike Angle(180.51 deg.N)

Strike Angle (deg.)

Strike Angle (deg.)

Figure 3.3.4-1 Example of examination of the effect of fault strike on the maximum water level ascentin the eastern margin of the Japan Sea
Figure 3.3.4-2 shows the plane position, distribution of maximum water level ascents along thecoastline and the effect of strike at each point for the examined tsunami sources. The fault models

Appendix 3 - 10

(tsunami earthquakes along sea trenches) were configured so that MW=8.2, L=200 km, W=50.0 km,
Slippage D=7.18 m, as well as δ=20° and λ=95° and d=1 km are the same for five cases, and only
strike is varied. By varying strike, points are also seen where the magnitude of reference strike varies
between 0.6 and 1.5 times. Also, just as in Figure 3.3.4-1, there is a tendency for the maximum waterlevel ascent to be greater at strike where the fault is upright with respect to the target point.

Soma
Reference Strike Angle(210 deg.N)

HironoHitachi

Relative ratio of max. water level ascentKatsuura

Soma
HironoHitachi
Katsuura

Strike Angle (deg.)

Figure 3.3.4-2 Example of influence of fault strike on the coastal maximum water level distribution
along the Japan Trench

Appendix 3 - 11

3.3.5. Effect of dip direction and angle(1) Effect of dip direction and angle
Figure 3.3.5-1 shows cases where the effect has been examined of fault dip direction for fivetsunami sources along the eastern margin of the Japan Sea. The same model is used for parameters
other than dip direction, and computing the ratio of the maximum water level ascent as a western
dip/eastern dip, the occurrence probability distribution is shown for each target point position(Shakotan-Misaki, Matsumae, Fukaura and Sakata). The fault models were configured using a
combination of conditions where MW was set between 7.4 and 7.8, thickness of the seismogenic
layer at 15 km and 20 km, δ at 30° and 60°, λ=90°, and d=0 km. Although tendencies differ
depending upon the target point in a relative comparison of the maximum water level ascent incases where the fault has a westerly dip and cases where the fault has an easterly dip, basically,
the ratio of the maximum water level ascent at all points was mainly distributed around 1.0, andno extreme variances have been established.

Appendix 3 - 12

Relative Frequency

Shakotan-Misaki

The ratio of the maximum water level ascent between west and east inclination

ShakotanMisaki
Relative Frequency

MatsumaeMatsumae

西傾斜と東傾斜の場合の最大水位上昇量の比
The ratio of the maximum
water level ascent between west and east inclination

FukauraSakataRelative Frequency

FukauraThe ratio of the maximum water level ascent between west and east inclination

Fault position

Relative Frequency

Sakata

西傾斜と東傾斜の場合の最大水位上昇量の比
The ratio of the maximum
water level ascent between west and east inclination

Figure 3.3.5-1 Examination of the influence of the dip direction of the fault in the eastern margin of
the Japan Sea on the maximum water level ascent(2) Effect of fault dip angle
Figure 3.3.5-2 shows examples of examinations conducted of the effect of dip angle for two
tsunami sources along the Japan Trench. The fault models for Fault (1) use the same parametersof MW=7.6, L=77 km, W=46.3 km, D=1.78 m, λ=85°, d=27 km, and Plane position, and the fault
models for Fault (2) (tsunami earthquake) use the same parameters of MW=8.2, L=200 km,
W=50.0 km, Slippage D=1.78 m, λ=95°, d=1 km, and Plane position. As may be seen for Katsuura,
there are cases where the effect on the dip angle due to target position is manifested significantly
in maximum water level ascent as well as cases where almost no effect is seen. In addition, evenat the same target point, there are cases where the tsunami source position affects the intensity ofthe effect of the dip angle as well as cases where the tendency of change is reversed.

Appendix 3 - 13

(1)

(2)

Max. Water Level Ascent (m)

Soma

Soma

HironoHitachi(1)

Dip Angle (deg.)

(1)

(2)

Max. Water Level Ascent (m)HironoKatsuura(2)

Dip Angle (deg.)(1)

Katsuura

(2)

(1)

(2)

Max. Water Level Ascent (m)Max. Water Level Ascent (m)HitachiDip Angle (deg.)

Dip Angle (deg.)

Figure 3.3.5-2 Examination of the influence of the dip angle of the fault on the maximum water levelascent in the sea area along the Japan Trench
3.3.6. Effect of slip angle
Figure 3.3.6-1 shows cases of examinations conducted of the effect of slip angle on tsunami
sources along the eastern margin of the Japan Sea, and Figure 3.3.6-2 shows cases of examinations
conducted where the tsunami sources are active faults in southwestern Japan.
Figure 3.3.6-1 shows the relationship between the target point and plane position of examinedtsunami sources as well as the effect of slip angle for each point. The fault models were configured so

Appendix 3 - 14

that MW=7.8, L=120 km, W=17.3 km, Slippage D=8.66 m, as well as a westerly dipping δ=60°, and
d=0 km are the same for five cases, and the slip angle was varied. There were four cases, the highest
number, in which there were points where the maximum water level ascent was the greatest when theslip angle was 90°.
Similarly, Figure 3.3.6-2 shows the relationship between target point and plane position of
examined tsunami sources as well as the effect of slip angle for each point. The fault models wereconfigured so that L=50 km, W=15 km, Slippage D=4.16 m, δ=90°, and d=0 km were the same for six
cases, and the slip angle was varied from 105° to 180°, which was the range estimated from theregional stress field. At all of the points, the maximum water level ascent was the greatest when the

Shakotan-Misaki

Relative Ratio of Max. Water level

Dip Angle (deg.)

Relative Ratio of Max. Water level

Relative Ratio of Max. Water level

slip angle was at 105°, which is the angle closest to a pure dip slip.

Matsumae

Dip Angle (deg.)

FukauraShakotanMisaki

Relative Ratio of Max. Water level

Dip Angle (deg.)

SakataMatsumae

FukauraFault position

SakataDip Angle (deg.)

Figure 3.3.6-1 Examples of examination of the influence of slip angle on maximum water level ascentin the eastern margin of the Japan Sea

Appendix 3 - 15DA

Relative Ratio of Max. Water level

Loc.B

Slip Angle (deg.)

Slip Angle (deg.)

Loc.C

Loc.D

Relative Ratio of Max. Water level

Relative Ratio of Max. Water level

C
Relative Ratio of Max. Water level

Loc.A

B

Slip Angle (deg.)

Slip Angle (deg.)

Figure 3.3.6-2 Examples of examination of the influence of slip angle on maximum water level ascent
where the tsunami source is an active fault in southwestern Japan
3.3.7. Effect of thickness of the seismogenic layer
In cases where the tsunami source is a seismic region along the eastern margin of the Japan Sea
or an active fault in southwestern Japan, the thickness of the seismogenic layer is assumed to be
between 15 and 20 km. If the seismic moment (moment magnitude) is considered to be equal, then achange in slip amount is inversely proportional to a change in the width of the fault plane such that
15km/20km=1.33 times. Examples of cases calculated where the tsunami sources are active faults insouthwestern Japan are shown in Figure 3.3.7-1.

Appendix 3 - 16

The fault models, which were examined and shown in Figure 3.3.7-1, were configured using a
combination of conditions where MW was set between 7.1 and 7.5, δ at 45°, 67.5° and 90°, λ between
105° and 180° (AF1) and between 110° and 180° (AF2), and d=0 km. A noticeable trend was observed
where the maximum water level ascent in a case, in which the seismogenic layer thickness was set at
15 km, was between 1 and 1.3 times that of a case where thickness was set at 20 km.

Max. Water level ascent (m)津波波高(m)（地震発生層15km）(Seismogenic
layer thickness 15km)

地点Ａ
Loc.A
3.0
y=1.33x

2.5

y=x

2.0
1.5
1.0
0.5
0.0
0.0

0.5 1.0 1.5 2.0 2.5 3.0
Max. Water level ascent (m),
津波高さ(m)（地震発生層20km）
thickness of S.L.=20km

Loc.B
地点Ｂ

Loc.C
地点Ｃ
Max. Water level ascent (m)津波波高(m)（地震発生層15km）(Seismogenic
layer thickness 15km)

Max. Water level ascent (m)(Seismogenic
layer thickness 15km)
津波波高(m)（地震発生層15km）

3.0
y=1.33x

2.5

y=x

2.0
1.5
1.0
0.5
0.0
0.0

0.5 1.0 1.5 2.0 2.5 3.0
Max. Water level ascent (m),
津波高さ(m)（地震発生層20km）
thickness of S.L.=20km

3.0
y=1.33x

2.5

y=x

2.0
1.5
1.0
0.5
0.0
0.0

0.5 1.0 1.5 2.0 2.5 3.0
Max. Water level ascent (m),
津波高さ(m)（地震発生層20km）
thickness of S.L.=20km*S.L. = Seismogenic layer

Figure 3.3.7-1 Example of examination of the influence of the thickness of the seismogenic layer on
maximum water level ascent in case of active fault in Southwest Japan as tsunami
source3.3.8. Effect of combining multiple segments
The Nankai Trough is comprised of multiple segments. Figure 3.3.8-1 shows changes in the
maximum water level ascent at target points along the coastline using combinations of hypothesized

Appendix 3 - 17

segment partitions (N1 alone, N2 alone, N1+N2, N3+N4, N2+N3+N4, and N1+N2+N3+N4). In cases
where multiple segments are taken into consideration, the timing also differs depending on the target
point when the waveforms of a tsunami striking from each segment will overlap with other tsunami.
Accordingly, it is difficult to find a clear correlation between earthquake energy and the maximum
water level ascent along the coastline such that the relationships are specific to the segment partition

Relative Ratio of Max. Water level ascentand target point.

Figure 3.3.8-1 Example of examination of the influence of the combination of segments along the
Nankai Trough on the maximum water level ascent

Appendix 3 - 18

3.3.9. Effect of fault plane shape and stress dropFigure 3.3.9-1 shows examples where the ratio of fault width to fault length was varied from 0.3
to 0.7 to examine the effect of the shape of fault planes along the Japan Trench. The fault models wereconfigured so that MW=8.1, D=3.15 m, δ=10° and λ=85° are the same for five cases, and the ratio
between width and length was varied. The trends, which showed a change in the maximum water levelascent differ depending upon the target point, are believed to be due to changes in response
characteristics and other factors accompanying changes in the basic inherent period as well as
propagation characteristics attendant upon the relative positional relationship with the tsunami source.
Figure 3.3.9-2 shows examples with respect to tsunami sources along the eastern margin of theJapan Sea where seismic moment was fixed and slip amount varied in keeping with the change in fault
length to examine the effect of static stress drop. The fault models were configured so that MW=7.8,
W=17.3km, westerly dipping δ=60°, d=0 km, and λ=90° are the same for five cases, and the fault
length was set at 0.8, 1.0 and 1.25 times the reference model (L=120 km). There are many points where
the maximum water level ascent is the highest when the slip angle is 90°. Also, there are many cases
showing a tendency for the maximum water level ascent to increase along with an increase in stressdrop.

Appendix 3 - 19

Relative ratio of max. water level ascent

Soma

HironoHitachi

Relative ratio of max. water level ascentKatsuura

Soma
HironoHitachi
Katsuura
W/L

Figure 3.3.9-1 An example of examination of the influence of the fault plane shape on the maximum
water level ascent in the sea area along the Japan Trench

Appendix 3 - 20

Matsumae
Relative ratio of max. water level ascent

Relative ratio of max. water level ascent

Shakotan-Misaki

Static Stress Drop △ 𝜎 (×106 N/m2)

Static Stress Drop △ 𝜎 (×106 N/m2)

FukauraRelative ratio of max. water level ascenteasterly dipping
δ=60°
westerly dipping
δ=60°
ShakotanMisaki

Static Stress Drop △ 𝜎 (×106 N/m2)
Matsumae

Relative ratio of max. water level ascent

SakataFukauraFault position

Sakata

静的応力降下量
StaticStress Drop △ Δσ（×10σ (×106 N/m62)N/m2）

Figure 3.3.9-2 Examples of examination of the influence of stress drop amount in the margin of eastern
margin of the Japan Sea on maximum water level ascent3.3.10. Effect of heterogeneity in fault dislocation
For earthquakes presumed to have a heterogeneous distribution of slip ( the 1968 earthquake off
the coast of Tokachi, the 1946 Nankai earthquake, and the 1983 earthquake in the central part of theJapan Sea), numerical simulations were conducted in which multiple slip distribution patterns wereconfigured by moving slip distribution rows and columns one at a time to yield a spatial distributionof the ratio of maximum water level ascent in heterogeneous models to homogeneous models, based
upon which assessments were conducted of the range of uncertainty and mean magnification between
the two. Also, a similar examination was also conducted of cases where heterogeneous models

Appendix 3 - 21

(asperity area, slip amount, etc.) were configured using the relationship presented by Somerville et al.
(1999) and the position of asperity was moved to configure multiple slip distribution patterns.
Figure 3.3.10-1 shows previously estimated heterogeneous models, Table 3.3.10-1 specificationsof fault models configured based upon Somerville et al. (1999), and Figure 3.3.10-2 methods forarranging asperity. In Table 3.3.10-1, the number of asperities is assumed to be two, the shape to besquare, and the quantities configured based upon Somerville et al. (1999). Figure 3.3.10-2 used amethod whereby a fault was divided into 2×3 small blocks. Maximum asperity is arranged in the centerof an arbitrary block, and the remaining asperity arranged within the remaining five blocks. The result isthe assumption of 6×5=30 fault models.

1968 Tokachi-Oki earthquake(Annaka et al., 1999)

1946 Nankai earthquake(Drawing based on Tanioka and Satake(1999))

1983 Nihonkai-Chubu earthquake(Fukuyama and Irikura, 1986)

Right figure: South fault smoothed for simplicity
Figure 3.3.10-1 Basic model of slip distribution based on estimated heterogeneous models

Appendix 3 - 22

Table 3.3.10-1 Parameters of fault models configured based upon Somerville et al. (1999)
Earthquake
Parameter

1968
Tokachi-Oki

1983
Nihonkai-Chubu

1946
Nankaistandard fault model

Aida (1978)

Satake (1985)

Tanioka and Satake(1999)

Total area of fault(km2)

15,0004,800

48,600

Seismic moment(N·m)

1.74×1021

3.16×1020

1.02×1022

405

229

729

Total area of asperity (km )

3,363

1,076

10,915

Area of largest asperity(km2)

2,448

784

7,946

Dislocation of asperity(cm)

813

460

1,465

Average dislocation(cm)2Seismic moment
Average dislocation
Total area of asperity
Area of largest asperity
Dislocation of asperity: With the area A known,
A=1.04×10-10×M02/3: D=3.36×10-5×M01/3: Aa=2.32×10-11×M02/3 (22% of A): A1=1.69×10-11×M02/3: Da=D×2.01

Largest asperity
Secondary asperity

Figure 3.3.10-2 Methods for arranging asperity
Table 3.3.10-2 shows the results of an assessment of mean magnification and variance in aheterogeneous model compared to a homogeneous model. The definitions of geometric mean and log
standard deviation are given below.
Geometric mean: log K 

1 N
 log K i
N i 1
1N2
Geometric standard deviation: log    1   log K i 2  log K 2  
 N  1  i 1

where, 𝐾
Assessments were conducted for each individual heterogeneous model, and the table shows therange, geometric mean, median value, and 84% non-exceedance value for all cases. The points ofAppendix 3 - 23comparison were the points where run-up height records of tsunami have been recorded for each
earthquake.
If the fault area and seismic moment are equal, then, as shown in the table, the homogeneousmodels provide a lower tsunami height on average than that of the heterogeneous models, so, in orderto obtain tsunami heights of the same magnitude, slip amount needs to be revised (increased).

Appendix 3 - 24

Table 3.3.10-2 Results of an assessment of mean magnification and variance in a heterogeneous modelcompared to a homogeneous model
1968 Tokachi-Oki
Model by Somerville et al.
(1999)

Model by Annaka et al.
(1999)

Ncalculation cases

30

10Number of points used for comparison

273

273

Geometric mean

K

Geometric
standard
deviation 

Range

1.280~1.597

1.060~1.358

Geometric mean

1.446

1.268

Median

1.466

1.325

84% cumulative

1.566

1.348

Range

1.191~1.385

1.221~1.355

Geometric mean

1.289

1.267

Median

1.279

1.251

84% cumulative

1.340

1.310

1946 Nankai
Model by Somerville et al.
(1999)

Model by Tanioka and Satake(1999)

Ncalculation cases

30

24

Number of points used for comparison
Geometric mean

K

Geometric
standard
deviation 

149

149

Range

1.100~1.542

1.589~2.510

Geometric mean

1.330

1.987

Median

1.351

2.023

84% cumulative

1.445

2.303

Range

1.267~1.453

1.338~1.670

Geometric mean

1.364

1.542

Median

1.376

1.570

84% cumulative

1.409

1.591

1983 Nihonkai-Chubu
Model by Somerville et al.
(1999)

Model by Fukuyama andIrikura (1986)

calculation cases

30

16

Number of points used for comparison

320

320

Range

1.053~1.310

0.998~1.162

Geometric mean

1.173

1.095

Median

1.168

1.099

84% cumulative

1.239

1.151

Geometric mean

K

Geometric
standard
deviation 

Range

1.186~1.379

1.130~1.240

Geometric mean

1.271

1.175

Median

1.266

1.169

84% cumulative

1.347

1.223

Appendix 3 - 25

3.3.11. Effect of tsunami source position and strike for the Chile tsunami (far-field tsunami)
Using the example of the Chile tsunami, an assessment was conducted that focused on analyzing
the sensitivity of variance resulting from uncertainty with respect to the tsunami source of a far-fieldtsunami. Figure 3.3.11-1 shows a map of the position of tsunami source models and a map of the
distribution of initial displacement. The plate boundaries and segment boundaries were taken into
account in configuring the tsunami source so that the position in Tsunami source model (1) for the1960 Chile tsunami was shifted 200, 400 and 600 km to the north. Also, the tsunami source wasconfigured such that strike was also ±10°. The default parameters are based upon Kanamori and Cipar(1974), but the Fault upper edge depth d was set at 1 km.
Figure 3.3.11-2 shows a comparison of the coastal distribution of tsunami height, and Table
3.3.11-1 the results of a comparison with run-up height records of tsunami. As for the reproducibilityof the run-up height records of tsunami, the value of variance κ does not change much for any of thetsunami sources. Also, the table shows the sensitivity of parametric studies to Tsunami source fault
model (1).

Appendix 3 - 26

(d)

(c)

(b)

(a)

Initialsurfacedisplacement(Case(a))
Plate boundary
Position of fault planes

Segment boundary★：Epicenter by Utsu (1990)

Figure 3.3.11-1 Tsunami source model position and initial surface displacement distribution of Chilean
tsunami (Added to the Chile tsunami joint study group (1961))

Appendix 3 - 27

Tsunami height (m)Confidence level of record
A
B
C
Unknown

Case 1Case 2
Case 3
Case 4

Ayukaw

OgatsuOnagawa

ShizugawaOkiraii

OfunatoRikuzentakatKesennuma

Kamaishii

YamadaOtsuchiMiyakoHachinohe
Taneichi
Kuji

River Takase

ShikabeToyouraYakumoMuroranMonbetsu

Tomakomai

Urakawa

Hiroo

Cape Erimo

Kushiro

Akkeshi

KiritappuHanasaki

Tsunami height (m)Case 1
Strike-10deg.
Strike+10deg.

Figure 3.3.11-2 Comparison of coastal distribution of tsunami height by assumed Chilean tsunami(Added to the Chile tsunami joint study group (1961))
Table 3.3.11-1 Comparison result by geometric mean (K) and geometric standard deviation (κ)
Case 1Case 2200 kmNorth

Case 3400 kmNorth

Case 4600 kmNorth

Strike-10deg.

Strike+10deg.

K

1.19

1.15

1.32

1.29

1.34

1.10

κ

1.43

1.41

1.39

1.42

1.43

1.41

K

-

1.03

0.90

0.92

0.89

1.08

ζ

-

1.18

1.20

1.28

1.15

1.18

K×ζ

-

1.21

1.08

1.17

1.02

1.28

Comparison

Observation/Calculation

Calculation/Case 1

Appendix 3 - 28

○Number of points
n= 586○Grid size aroundcomparison points
278m or 93m○ K: Geometric mean
κ: Aida(1977)’s
Geometric standard
deviation
ζ: Geometric standard
deviation (no bias)

3.3.12. Examination of the effect that kinematic parameters have on tsunami height
In this section we examine the effect of the hypocenter, rupture propagation velocity and rise timeon tsunami heights in the eastern margin of the Japan Sea.
(1) Examination conditions
Table 3.3.12-1 shows calculation settings for this examination, and Figure 3.3.12-1 shows
the computational region.
1) Hypocenter• Fault model: A model was developed which has an aggregation of small faults with 10 km longand 5 km wide.
• The relationship between fault area S and Seismic moment M0 is applied. However,heterogeneity of slip is not taken into consideration.
• A total of six hypocenters are configured at the southern edge, center and northern edge of thefault upper edge and lower edge, respectively.
2) Rupture propagation velocity
The rupture propagation velocity of 3.0 km/s is used as reference case, and those of 2.5
km/s and 3.5 km/s are done for parametric studies.
3) Rise time
The rise time of 0 seconds is used as reference case, and those of 10, 30, and 60 seconds
are used for parametric studies.
4) Calculation cases
Table 3.3.12-2 shows a list of the cases examined.
5) Tsunami source
Vicinity of the source region of the 1993 Hokkaido Nansei-Oki earthquake

Appendix 3 - 29

Table 3.3.12-1 Calculation conditions
Items

Contents

Computational
regionCalculation grid size

Offshore 1,600m, 800m, 400m, 200m

Basic equations

Nonlinear long wave equations

Initial displacement
fields of seafloor
Boundary conditions
Overflow conditions
Horizontal
eddy
viscosity coefficient
Coefficientoffriction
Tide conditions
Computation timeinterval
Simulating time

All over the Sea of JapanThe method of Mansinha and Smylie(1971)
Offshore: Open boundary condition (Tsugaru, Tsushima, La Perousestrait)Landward: Full reflection condition (for seafloor exposure, the moving
boundary method of Kotani et al.(1998) applied)None
10m2/sManning's coefficient of roughness: 0.03m-1/3s
T.P.±0.0m
0.5s
6 hours after the occurrence of earthquake

Figure 3.3.12-1 Computational region

Appendix 3 - 30

Table 3.3.12-2 List of cases
Item
Fracture initiation
point
Fracture
propagation
velocity
Fracture
propagation
velocity+rise time

Hypocenter

Rupture propagation
velocity

Rise time

1-6 (6 points)

3.0km/s0s

12.5, 3.0, 3.5km/s

0s

1

3.0km/s

0, 10, 30, 60s-∞

0, 10, 30, 60s

Rise time(2) Examination of tsunamis in the vicinity of the source region of the 1993 Hokkaido Nansei-oki
earthquake (tsunami source designation: E1C2)
An examination is conducted in which a rectangular fault with a fault width of 28.28 km anda length of 167.1 km is arranged in the vicinity where the 1993 Hokkaido Nansei-oki earthquake
occurred (E1C1). As shown in Figure 3.3.12-2, small faults are arranged dividing the area into
five equal parts across the width and 16 equal parts across the length. This examination does nottake into account large slip areas, and a configuration of uniform slip (4.53 m) is used.
Figure 3.3.12-3 shows the horizontal distributions of the water level for various cases whenseafloor displacement ends, and Figures 3.3.12-4 through 3.2.12-6 show the same ones after 85
seconds, 5 minutes, and 10 minutes, respectively. Although differences are observed in tsunami
when seafloor displacement ends and when 85 seconds have elapsed after seafloor displacement
ended, no significant differences are existed in tsunami after 5 minutes had passed as well as after
10 minutes had passed.
1) Examination of hypocenter
Hypocenters are configured at six points (a) through (f) (Figure 3.3.12-2) and a tsunami
analysis conducts to compare tsunami heights along the coastline. Diagrams comparing
tsunami heights along the coastline from Hokkaido to Kyoto are shown in Figures 3.3.12-7
through 3.3.12-10, and Figure 3.3.12-11 shows a diagram comparing the tsunami heights at
Okushiri Island.
• Overall, there is a tendency that tsunami heights are lower than that of instantaneous overall
rupture.
• In the vicinity of tsunami source, there are points where the difference in the tsunami height

Appendix 3 - 31

is significant with respect to instantaneous overall rupture.
• In cases where the rupture starts from the center of the tsunami source (hypocenters (b)and (e)), there are points where the tsunami height on the northern side of the tsunami
source is higher than that of instantaneous overall rupture.
• In the area around Inaho (area around the northern tip of Okushiri Island) (Figure 3.3.1221), the tsunami height is predominantly higher than that of instantaneous fracture(Fracture initiation points (a), (c), (d) and (f)).
2) Examination of rise time
An examination is conducted where rise time is set at 10, 30, and 60 seconds. In thisexamination, the hypocenters are not set, and simultaneous rupture is used. Figure 3.3.12-12shows the results of a comparison of tsunami heights along the coastline from Hokkaido to
Kyoto, and Figure 3.3.12-13 shows the results of a comparison of tsunami heights at Okushiri
Island.
• Overall, there is a tendency that tsunami heights are lower than that of instantaneous
fracture.
• At points near tsunami sources, the tsunami height is significantly lower when the rise timeis 60 seconds.
• Although the tsunami height is significantly lower when rise time is 60 seconds, there islittle impact on the other side of Okushiri Island as viewed from the tsunami source (e.g.
Hotokesawa).
3) Examination of rupture propagation velocity
An examination is conducted where fracture propagation velocity is set at 2.5, 3.0, and3.5 km/s. In these cases, the examination is conducted by fixing the fracture initiation point at(a). Figure 3.3.12-14 shows the results of a comparison of tsunami heights along the coastline
from Hokkaido to Kyoto, and Figure 3.3.12-15 shows the results of a comparison of tsunami
heights at Okushiri Island.
• Lower tsunami heights are existed at points far from the hypocenter in the vicinity of thetsunami source.
• Overall, there is a tendency that tsunami heights are lower than that of instantaneous
rupture.
• When rupture propagation is taken into account, tsunami height on the northern tip ofOkushiri Island is higher when compared with that of instantaneous rupture, but thedifference resulting from different fracture propagation velocities is small.
• Of the cases in this examination, the tsunami height at the Inaho when the rupture

Appendix 3 - 32

propagation velocity is 2.5 km/s is the highest (T.P.+11.3 m).
4) Examination of tsunami superposition
An examination is conducted in which the rupture propagation velocity is set at 3.0 km/s,
the hypocenter fixed at (a), and the rise time varies: 0 second, 10 seconds, 30 seconds, and 60
seconds. Figure 3.3.12-16 shows the results of a comparison of tsunami heights along thecoastline from Hokkaido to Kyoto, and Figure 3.3.12-17 shows the results of a comparison oftsunami heights at Okushiri Island.
• In the vicinity of the tsunami sources, the tsunami height is somewhat higher for rise timeof 10 seconds.
• Overall, there is a tendency that tsunami heights are lower than that of instantaneous
rupture.
• In the area around Inaho (area around the northern tip of Okushiri Island), tsunami heights
result in a predominantly higher than that of instantaneous rupture (hypocenters (a), (c),(d) and (f)).
• Tsunami heights are somewhat lower than that of the case where only the rupture
propagation velocity is taken into account.
5) Analysis of factors where the difference is greater
In the examination of the effect of hypocenters, results are shown (Figures 3.3.12-18 and3.3.12-19) where the difference in the maximum tsunami heights is greater around Sakaeiso
on the Hokkaido coastline (Figure 3.3.12-20) and around Inaho on Okushiri Island (Figure
3.3.12-21).
Figure 3.3.12-22 shows a diagram comparing time histories of the water level at therespective points. The difference in peak heights at around 15 minutes at Inaho is thought tobe caused by the superposition of waves propagating around to the north along the coastline of
Okushiri Island and the wave propagating along the south of the island (Figure 3.3.12-23).
In order to verify that the difference in tsunami height at Inaho is caused by thesuperposition of waves propagating along the coastline of Okushiri Island, an examination isconducted of cases where only one portion of the tsunami source ruptures. Snapshots are shownof the tsunami heights around Inaho (Figures 3.3.12-25 and 3.3.12-26). It is verified that thewave, which arrives at the northwestern part of the island from the vicinity of the center of thetsunami source (hypocenter (b)), propagates to the north, and superimposes with the wave
propagating along the eastern coastline from the south of the island from around the southernpart of the tsunami source (hypocenter (c)), thereby resulting in amplification of the tsunami
height at Inaho.

Appendix 3 - 33

Based on the aforementioned, it is found that, in cases where there are islands,
promontories or other geographical features around a tsunami source, the effects of the
hypocentral position and rupture propagation velocity may amplify tsunami height by between
20 and 30%.

Figure 3.3.12-2 Hypocenters of the fault model (the vicinity where the 1993 Hokkaido Nansei-oki
earthquake occurred)

Appendix 3 - 34

Figure 3.3.12-3 Comparison of the horizontal distribution of tsunami height (when grounddeformation ended)

Appendix 3 - 35

Figure 3.3.12-4 Comparison of the horizontal distribution of tsunami height (85seconds later)

Appendix 3 - 36

Figure 3.3.12-5 Comparison of the horizontal distribution of tsunami height (5 minutes later)

Appendix 3 - 37

Figure 3.3.12-6 Comparison of the horizontal distribution of tsunami height (10 minutes later)

Appendix 3 - 38

Figure 3.3.12-7 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): examinationof hypocenters (all cases)

Appendix 3 - 39

TeppuTeuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

14

12

10

8

6

4

2

0
Tsunami Water Level(ｍ)

14

12

10

8

6

4

2

0

Tsunami Water Level(ｍ)Instantaneous Fracture

18(a)Fracture Initiation Point-1

20

16

20

(b)
Fracture Initiation Point-2

18

16

Instantaneous Fracture

Teppu
Teuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

Figure 3.3.12-8 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): examinationof hypocenters (a), (b)Appendix 3 - 40

TeppuTeuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

14

12

10

8

6

4

2

0
Tsunami Water Level(ｍ)

14

12

10

8

6

4

2

0
Tsunami Water Level(ｍ)16Instantaneous Fracture
18(c)Fracture Initiation Point-3

20

20

(d)
Fracture Initiation Point-4

18

16

Instantaneous Fracture

Teppu
Teuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

Figure 3.3.12-9 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): examinationof hypocenters(c), (d)Appendix 3 - 41

TeppuTeuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

14

12

10

8

6

4

2

0

Tsunami Water Level(ｍ)

14

12

10

8

6

4

2

0
Tsunami Water Level(ｍ)1616Instantaneous Fracture
18(f)Fracture Initiation Point-6

20

Instantaneous Fracture
18(e)Fracture Initiation Point-5

20

Teppu
Teuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

Figure 3.3.12-10 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto):

examination of hypocenters (e), (f)Appendix 3 - 42

Figure 3.3.12-11 Comparison of tsunami heights along the coastline (Okushiri island): examination of
hypocenters (all cases)

Tsunami Water Level(ｍ)E1C2(The vicinity where an earthquake occurred southwest off the coast of Hokkaido)K, κ were calculated by Aida(1979)【The examination of fracture initiation points】 (regards results of instantaneous fracture as observed values)
・Rise time 10, 30, 60s
Kκ
・The fracture initiation points are not set
1.00
1.01
Rise time 10s
20

Rise Time 10s

18

Rise Time 30s

16

Rise Time 60s

14Instantaneous Fracture

Rise time 30s
Rise time 60s

1.03
1.09

1.02
1.07

12
10
8
6
4
2
0

Teppu
Teuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

Figure 3.3.12-12 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): rise time

Appendix 3 - 43

Figure 3.3.12-13 Comparison of tsunami heights along the coastline (Okushiri island): rise timeE1C2(The vicinity where an earthquake occurred southwest off the coast of Hokkaido)

Tsunami Water Level(ｍ)【The examination of fracture initiation points】
・Fracture propagation velocity 2.5, 3.0, 3.5km/s
・The fracture initiation points are fixed (a)20

Fracture Propagation Velocity 3.0km/s

18Fracture Propagation Velocity 2.5km/s

16Fracture Propagation Velocity 3.5km/s

14Instantaneous FractureK, κ were calculated by Aida(1979)(regards results of instantaneous fracture as observed values)κK

Fracture propagation velocity 2.5km/s
Fracture propagation velocity 3.0km/s
Fracture propagation velocity 3.5km/s

1.03
1.04
1.04

1.12
1.12
1.11

12
10
8
6
4
2
0

Teppu
Teuri
Bakkai
Syosanbetsu
Rumoi
Gokibiru
Asari Coast
Syakotan Riv. Right
KawashiraShibui
Iwanai PortBiya
Kobecyanai Riv.
Nagatoyo
Harauta
Baba Riv.
HutoroHirahama
Toyohama
Esashi
Chiisago
Kodomari Port
Takinoma
Ochiai
Gomyoukou
Nishikurosawa Port
Masukawa Port
Iwaki
Kamitakayahama
Kosagawa Port
Yura Port
Huya
Sasagawa
IwahuneTaroudai
Echizenhama
Inohana
Yotsuyahama
Hime Riv.
Ukawa
Takojima
KinouraOosawa Port
Saruyamasaki
Hukui Oil Terminal
Kaburaki
Sugahama
Tomari
Otomi
Nohara
Hioki
Nakahama
Asahifunabiki Slope

Figure 3.3.12-14 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): rupture
propagation velocity

Appendix 3 - 44

Figure 3.3.12-15 Comparison of tsunami heights along the coastline (Okushiri island): rupture
propagation velocity

Figure 3.3.12-16 Comparison of tsunami heights along the coastline (Hokkaido to Kyoto): rupture
propagation velocity + rise time

Appendix 3 - 45

Figure 3.3.12-17 Comparison of tsunami heights along the coastline (Okushiri island): rupture
propagation velocity + rise time

Appendix 3 - 46

*”Dynamic fracture” refers to consideration of hypocenter or rupture propagation velocity.

Figure 3.3.12-18 The points with larger difference from the case of instantaneous rupture (the coast of
Hokkaido)

Appendix 3 - 47

*”Dynamic fracture” refers to consideration of hypocenter or rupture propagation velocity.

Figure 3.3.12-19 The points with larger difference from the case of instantaneous rupture (the coast of
Okushiri island)

Appendix 3 - 48

Figure 3.3.12-20 The points with larger difference from the case of instantaneous rupture (the coast of
Hokkaido)

Appendix 3 - 49

Figure 3.3.12-21 The points with larger difference from the case of instantaneous rupture (the coast of
Okushiri island)

Appendix 3 - 50

Figure 3.3.12-22 Comparison of the time histories of water level at Sakaeiso and Inaho

Figure 3.3.12-23 The difference of the maximum water level ascent around Okushiri island(examination of hypocenter – instantaneous fracture)

Appendix 3 - 51

Figure 3.3.12-24 Patterns of partial rupture of the fault plane (the shade area indicates the partial
fracture)

The entire fracture(d)v00_no00_rt00 Instantaneous Fracture
v30_no01_rt00 Fracture Initiation Point①
Point (a)

(a)

(e)

(b)

(f)

(c)

Water Level(m)Point (b)v30_no08_rt00 Fracture Initiation Point②
Point (c)V30_no16_rt00 Fracture Initiation Point③

12
10
8
6
4
2
0
‐2
‐4
‐6
0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Time(min)v00_no00_rt00 Instantaneous Fracture

The partial fracture

v30_no01_rt00 Fracture Initiation Point①
Point (a)Water Level(m)v30_no08_rt00 Fracture Initiation Point②
Point (b)
14
12
10
8
6
4
2
0
‐2
‐4
‐6

V30_no16_rt00 Fracture Initiation Point③
Point (c)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Time(min)Figure 3.3.12-25 Comparison of the time histories of water level at Sakaeiso and Inaho (the upper: theentire fracture, the lower: the partial rupture)

Appendix 3 - 52

Fracture initiation point (a)Fracture initiation point ( b)Fracture initiation point ( c)Figure 3.3.12-26 Horizontal distributions of the maximum water level ascent (from above, 7.5 min.
later, 10 min. later, 12.5 min. later, 15 min. later)

Appendix 3 - 53

(4) Summary
The examination was conducted of the effect that the hypocenter, rupture propagation
velocity, and rise time have on tsunami height along the eastern margin of the Japan Sea. Basedon the examination results, there is an overall tendency for tsunami height to be lower when the
hypocenter or other elements are taken into consideration, but because there are some local points
where the tsunami height is around 20 to 30% higher, particular care needs to be given to points
having specific features such as those described below.
• Points that are near the tsunami source and the case that the effect of first wave is large• Points that are significantly affected by islands• Points that are significantly affected by promontories or peninsulas• Points that are in a bay and are significantly affected by reflected waves
In addition, in cases where the tsunami height is relatively higher in cases of instantaneous
fracture, it is desirable to perform calculations that take into account rupture propagation velocity
and rise time for the benefit of verification.

[Appendix 3 References]
Aida, I. (1977): Simulations of Large Tsunamis Occurring in the Past off the Coast of the Sanriku
District., Bulletin of the Earthquake Research Institute, University of Tokyo, Vol. 52 (1), pp.
71-101 (in Japanese).
https://repository.dl.itc.utokyo.ac.jp/?action=repository_action_common_download&item_id=33218&item_no=1&att
ribute_id=19&file_no=1
Annaka, T., K. Ohta, H. Motegi, I. Yoshida, M. Takao and H. Soraoka (1999): Tsunami Inversion
Based on the Shallow Water Theory, Proceedings of Coastal Engineering, JSCE, Vol. 46, pp.
341-345 (in Japanese).
https://www.jstage.jst.go.jp/article/proce1989/46/0/46_0_341/_pdf/-char/ja.
Committee for the Field Investigation of the Chilean Tsunami of 1960 (1961): The Chilean tsunami of
May 24, 1960, Earthquake Research Institute, The University of Tokyo, 397p. (in Japanese).
http://iss.ndl.go.jp/books/R100000039-I000797416-00.
Fukuyama, E. and K. Irikura (1986): Rupture process of the 1983 Japan Sea (Akita-Oki) earthquake
using a waveform inversion method, Bulletin of the Seismological Society of America, Vol.
76:6, pp. 1623-1640.
Kanamori, H. and J. J. Cipar (1974): Focal process of the great Chilean earthquake May 22, 1960,

Appendix 3 - 54

Phys. Earth Planet. Interiors, Vol. 9 pp. 128-136.
Kotani, M., F. Imamura. and N. Shuto (1998): New method of tsunami runup and estimation of damage
using GIS data, Proceedings of Coastal Engineering, JSCE, Vol. 45, pp. 356-360 (in Japanese).
http://library.jsce.or.jp/jsce/open/00008/1998/45-0356.pdf
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